Tech Jargon - Decoded

What is Throughput? Throughput is the actual amount of data or tasks a system successfully processes within a specific timeframe. It represents the real-world performance of a link or process. How it works: - It measures the flow of data from the source to the destination. - It counts only the completed units (bits, packets, or requests) per second. - It accounts for delays, errors, and overhead that might slow down the transfer. Problem it solves: - It identifies bottlenecks where data gets stuck. - It helps distinguish between theoretical capacity (Bandwidth) and actual delivery speed. Simple Scenario: If a server receives 100 requests but can only process 60 in one second, the Throughput is 60 requests per second (RPS). This helps in scaling the system to match the incoming load.

What is Latency? Latency is the time delay between a data request being sent and the response being received. It is the measure of time it takes for a signal to travel across a system or network. How it works: • A command is converted into data packets at the source. • These packets travel through physical hardware like cables, routers, and switches. • Each component takes a few milliseconds to process and forward the data. • The destination receives the packet and sends an acknowledgment back. • The total duration of this round-trip is the measured latency. Problem it solves: Managing latency prevents "lag." By minimizing the delay, systems stay synchronized, ensuring data arrives fast enough to be used immediately without stalling. Scenario: A computer sends a signal to a server. If the signal takes 30ms to arrive and the reply takes 30ms to return, the total latency is 60ms.

What is Throttling? It is a technique used to limit the execution of a function to once every fixed time interval. It ensures a piece of code doesn't run too often, even if the event triggering it happens repeatedly. How it works: • An event triggers the function. • The function executes and starts a "cool-down" timer. • Any further triggers are blocked while the timer is active. • Once the time is up, the next trigger is allowed to execute again. Problem it solves: It prevents performance degradation and system lag caused by high-frequency events that would otherwise overwhelm the CPU or network. Use Case: During a window resize event. Instead of recalculating the layout 60 times a second, throttling forces it to update only once every 200ms to keep the UI smooth.

What is Rate Limiting? It is a strategy used to control the number of requests a client can make to a server within a specific timeframe. How it works: • The server tracks the number of requests coming from a specific source (like an IP address). • It checks this count against a predefined limit (e.g., 50 requests per minute). • If the limit is exceeded, the server rejects any further requests from that source. • Once the time window expires, the counter resets and access is restored. Problems it solves: • Prevents server crashes caused by sudden traffic spikes. • Blocks brute-force attacks on login or sensitive endpoints. • Stops automated scripts from over-consuming system resources. Simple Scenario: An API allows 5 requests per second. If a script tries to send 50 requests at once, the server processes the first 5 and blocks the remaining 45 with a "429 Too Many Requests" error.

What is a Load Balancer? It is a tool that acts as a "traffic controller" between users and your servers. It ensures that no single server carries too much load by spreading incoming requests across a group of servers. How it works: • A user sends a request to access an application. • The Load Balancer receives the request first. • It checks which backend servers are online and how busy they are. • It uses a rule (like Round Robin) to forward the request to the best server. • The server processes the request and sends the response back. Problem it solves: • Server Overload: Prevents a single server from crashing due to high traffic. • Single Point of Failure: If one server dies, the balancer shifts traffic to healthy ones so the site stays live. Simple Scenario: Imagine you have 1,000 users. Instead of all 1,000 hitting one server and slowing it down, a Load Balancer sends 500 users to Server A and 500 to Server B, keeping the response time fast for everyone.

What is a Forward Proxy? It is an intermediary server that sits between a user (client) and the internet. Instead of your device connecting directly to a website, it sends the request to the proxy, which then talks to the web on your behalf. How it works: • Client sends a request to the proxy server. • Proxy receives the request and checks its rules. • Proxy forwards the request to the destination web server. • The web server sends the response back to the proxy. • Proxy passes that response back to the client. Problems it solves: • IP Masking: The destination server only sees the proxy's IP, keeping the client's identity private. • Access Control: Can be used to block specific websites or content. • Caching: Stores local copies of data to speed up repeated requests. Simple Scenario: In a restricted office network, every employee's computer sends web requests to a central proxy. The proxy ensures no one visits restricted sites and hides the internal network structure from the outside world.

What is a Reverse Proxy? It is an intermediary server positioned between client devices and backend web servers. It intercepts requests from users and forwards them to the appropriate internal server. How it works: • A user sends a request to the proxy's address. • The proxy receives the request and selects a backend server. • It communicates with that server on behalf of the user. • Once the server responds, the proxy sends that data back to the user. Problems it solves: • Server Anonymity: Keeps internal server IP addresses private. • Traffic Congestion: Distributes incoming requests across multiple servers. • SSL Offloading: Manages encryption, reducing the load on backend servers. Use case: Directing traffic to multiple identical servers to prevent any single one from crashing during high traffic periods.

What is a Content Delivery Network (CDN)? It is a system of distributed servers that work together to provide fast delivery of Internet content by placing data closer to where the users are. Problem it Solves: • Latency: Fixes the delay caused by data traveling long physical distances. • Origin Congestion: Prevents the main server from crashing by distributing the traffic load. How it Works: 1. Copies of static files (images, scripts, videos) are stored on multiple "Edge Servers" globally. 2. When a user requests a file, the CDN identifies their geographic location. 3. The request is routed to the server physically closest to that user. 4. The local server delivers the cached data immediately. Simple Scenario: A user in Tokyo wants to access a file from a server located in London. Instead of the data traveling across the globe, a Tokyo-based CDN node provides the file directly, making the load time nearly instant.

What is DNS (Domain Name System)? It is a system that translates human-readable domain names into machine-readable IP addresses. It acts as a directory for the internet. The Problem it Solves: Computers identify each other via IP addresses (like 192.0.2.1), but humans cannot memorize these numbers for every site. DNS removes this burden by allowing the use of names. How it works: • You enter a domain name in your browser. • Your device sends a query to a DNS Resolver. • The resolver checks its cache or queries Root and TLD (.com, .net) servers. • It eventually reaches the Authoritative Name Server which holds the actual IP. • This IP is sent back to your browser to initiate the connection. Use Case: Locating the specific server where a website's data is stored without needing to know its hardware address.

What is Long Polling? It is a web communication technique used to get real-time updates from a server without the client asking repeatedly every second. How it works: • The client sends a request to the server for data. • If the server has no new info, it holds the connection open instead of sending an empty "no" response. • The connection stays hanging until data is available or a timeout occurs. • Once the server has data, it sends the response back. • The client receives the data and immediately sends a new request to start the cycle again. Problem it solves: It stops "Short Polling" issues where a client wastes bandwidth and CPU by constantly asking "Is there data yet?" and getting empty responses. Use Case: A scenario where data updates are unpredictable. The client stays "on the line" so it can receive data the millisecond it becomes available on the server.

What is Polling? Polling is a technique where a client repeatedly requests data from a server at fixed intervals to check for updates. How it works: • The client sends an HTTP request to the server. • The server checks its current state or database for new info. • The server sends a response immediately (with data or an empty status). • The client waits for a defined time (e.g., 5 seconds). • The process repeats indefinitely or until a condition is met. Problem it solves: • It allows a client to stay updated when the server cannot "push" data. • It provides a way to sync data over standard HTTP without persistent connections. Simple Scenario: A browser needs to show the status of a long-running background task. The script sends a GET request every 3 seconds to fetch the current completion percentage until the task returns a "Finished" status.

What are WebSockets? A protocol that allows a persistent, full-duplex connection between a client and a server over a single TCP connection. Problem Solved: • Eliminates the need for "Polling" (where the client repeatedly asks for data). • Removes the heavy overhead of sending HTTP headers back and forth for every tiny update. The Working: • Handshake: The client sends an HTTP request with an "Upgrade" header. • Switch: The server accepts and switches the protocol from HTTP to WS. • Open Pipe: A dedicated "pipe" is created that stays open. • Bi-directional: Both the client and server can push data packets to each other at any time without waiting for a request. Use Case Scenario: In a data dashboard, the server pushes new data packets to the UI the millisecond they change, rather than the browser refreshing or asking for updates every few seconds.

What is gRPC? It is a high-performance framework that allows a program to call a function on a different machine as if it were a local function call. How it works: • IDL: You define service methods and data structures in a .proto file. • Protobuf: It serializes data into a small binary format instead of heavy text like JSON. • HTTP/2: It uses a single connection to send multiple messages at once, reducing setup time. • Stubs: The client uses a "stub" (a local proxy) to talk to the server, hiding the network complexity. Problem it solves: Standard REST APIs can be slow due to bulky JSON and overhead. gRPC makes communication between microservices much faster and uses way less bandwidth. Scenario: A Java service needs data from a Go service. It calls a GetRecords() method. gRPC handles the data conversion, sends it over the wire, and triggers the logic in the Go service instantly.

What is GraphQL? GraphQL is a query language for APIs and a runtime for fulfilling those queries with your data. It gives clients the power to ask for exactly what they need and nothing more. How it works: • Schema: You define a blueprint of your data types and their relationships. • Query: The client sends a request specifying the exact fields they want. • Single Endpoint: All requests are sent to a single URL, regardless of the data needed. • Resolvers: The server uses functions to fetch only the requested data and returns it in JSON format. Problems it solves: • Over-fetching: No more receiving extra data you won't use. • Under-fetching: Avoids making multiple API calls to get related data; you get it all in one trip. Scenario: If you need a "User Name" and "Post Titles," you send one query asking for those specific fields. The server returns exactly that, avoiding multiple round-trips to the database.

What is REST? REST is an architectural style for designing APIs. It defines a set of rules that allow a client and a server to exchange data over the HTTP protocol. How it works: • The client sends a request to a specific URL (endpoint). • It uses HTTP methods: GET (read), POST (create), PUT (update), or DELETE. • The server processes this and returns data, usually as JSON. • It is stateless, meaning the server doesn't store any session data; every request must contain all the info needed to handle it. Problem solved: It eliminates platform dependency. A website in JavaScript can talk to a server in Python without needing to know how the server is built. Scenario: A mobile app sends a GET request to /users/10. The server finds user 10 in the database and sends back their profile details as a JSON object.

What is HTTPS and how does it work? HTTPS is the secure version of HTTP. It ensures that all data sent between a browser and a server is encrypted and kept private. Problem it solves: Standard HTTP sends data in plain text. This allows hackers to intercept and read sensitive info like passwords. HTTPS prevents this "eavesdropping" by scrambling the data. How it works: • Handshake: The browser and server connect and agree to communicate securely. • Certificate Check: The server sends an SSL certificate to prove its identity. • Key Exchange: Both sides generate a unique "secret key" for the session. • Encryption: Data is turned into unreadable code before being sent. Only the receiver can unlock it using the key. Simple Scenario: When you type a password into a form, HTTPS converts it into a random string of characters before it travels across the internet, making it useless to anyone who steals it.

How does TCP/IP enable internet communication? It is a set of rules that governs how data is sent across networks. It ensures that information moves accurately between devices. The Working: • Packetizing: TCP breaks data into small pieces so they move easily. • Addressing: IP assigns a destination address to every piece. • Routing: Routers read the IP and forward data toward the destination. • Reliability: TCP waits for confirmation. If a piece is lost, it is sent again. • Sequencing: The receiver reorders the pieces to recreate the original data. Problem Solved: Fixes the issue of "unreliable networks." It handles data loss and packet congestion automatically so the user gets a perfect copy without errors. Scenario: When opening a website, your request is split into packets. Even if some packets arrive late or out of order, TCP/IP reassembles them so the page displays correctly.

What is TCP/IP? It is the standard set of rules that allows computers to communicate across a network. It acts as the basic "language" of the internet. How it works: • TCP (Transmission Control Protocol): Breaks data into small chunks called packets. It numbers them and ensures they arrive safely. If a packet goes missing, it requests a resend. • IP (Internet Protocol): Handles the addressing. It labels each packet with the source and destination IP addresses so routers know where to send them. Problem it solves: It prevents data loss and corruption. Without it, data sent over long distances would arrive scrambled or incomplete, and different types of hardware wouldn't be able to talk to each other. Simple Scenario: When you fetch a webpage, TCP breaks the page data into packets. IP routes these packets through various servers to your device. TCP then checks that every packet arrived and puts them back in the correct order to display the site.

What does it mean for a process to be CPU Bound? It refers to a situation where the speed of a task is limited by the processor's performance. The execution progress depends entirely on how fast the CPU can crunch numbers and run logic. How it works: • The CPU stays at nearly 100% usage during the task. • The program spends most of its time executing instructions in the register/cache. • It rarely waits for data from the hard drive or the network. • If you upgrade to a faster processor, the task completes in less time. Use Case Scenario: Performing heavy mathematical calculations or data encryption. The system is stuck waiting for the next logic cycle to finish before it can move to the next step of the algorithm. Problem it solves: It allows the system to maximize raw computational throughput when data is already available in memory, ensuring no processor cycles are wasted sitting idle.

What is I/O Bound? I/O bound refers to a state where the execution of a program is limited by the speed of Input/Output operations rather than the processor. • How it works: - The CPU executes its tasks extremely quickly. - It then makes a request to an external source, like a disk, a database, or a network. - The CPU must sit idle (wait) until that external source sends the data back. - The total time taken depends almost entirely on the speed of the I/O device. • Why it matters: - It helps you identify that upgrading your CPU won't improve performance. - It shows when to use asynchronous programming or multithreading to keep the CPU busy with other tasks while waiting. • Simple Scenario: A script fetching data from a web API. The CPU finishes its logic in 1ms but stays idle for 200ms waiting for the network response. The task is limited by the network speed, not the code speed.