Tech Glossary
Plain-English definitions of the terms that developers and curious users end up searching for: APIs, webhooks, CORS, DNS, encryption, OAuth, and more. Each entry is short enough to read in under two minutes and links to the Utilko tools you'd actually use when working with that concept.
What Is an API? Plain-English Explanation + Examples
An API (Application Programming Interface) is a defined way for one piece of software to ask another for data or work. Clear explanation with REST, GraphQL, and public API examples.
What Is Base32? (And Why It's Different from Base64)
Base32 encodes binary data using 32 ASCII characters (A-Z, 2-7). Used for QR codes, TOTP secrets, and case-insensitive systems. Plain explanation with examples.
What Is Big O Notation? (Explained with Real Examples)
Big O notation describes how an algorithm's time or memory grows as input gets larger. Plain explanation of O(1), O(n), O(log n), O(n²) with code examples.
What Is a CDN? Why Websites Load Fast Everywhere
A CDN (Content Delivery Network) is a global network of servers that caches your website's assets close to users. Explanation of edge caching, pop locations, and why it matters.
What Is CORS? The Browser Security Rule, Explained
CORS (Cross-Origin Resource Sharing) is how browsers decide whether a web page can call an API at a different origin. Plain explanation of origins, preflights, and how to fix common CORS errors.
What Is DNS? How Your Browser Finds Websites
DNS (Domain Name System) is the global lookup service that converts domain names like utilko.com into IP addresses your computer can connect to. Clear explanation of records, recursion, and caching.
What Is Encryption? Symmetric, Asymmetric, and When to Use Each
Encryption scrambles data so only someone with the key can read it. Clear explanation of symmetric (AES) and asymmetric (RSA) encryption, hashing, and common real uses.
What Is gRPC? Modern RPC Framework, Plain English
gRPC is Google's high-performance RPC framework using HTTP/2 and Protocol Buffers. Faster than REST for service-to-service traffic. Clear explanation with use cases.
What Is an HTTP Cookie? How Web Sessions Actually Work
A cookie is a small piece of data a website stores in your browser that gets sent back with every subsequent request. Explanation of session cookies, flags, and third-party cookies.
What Is an IP Address? Public vs Private, IPv4 vs IPv6
An IP address is the unique identifier assigned to any device on a network — how the internet knows where to send data. Clear explanation of IPv4, IPv6, public vs private, and static vs dynamic.
What Is JSONP? (And Why You Probably Shouldn't Use It)
JSONP is a workaround from before CORS that loaded JSON across origins via a <script> tag. Modern code should use CORS instead — but legacy APIs still expose JSONP.
What Is a JWT Signature? (And How to Verify One)
A JWT signature cryptographically binds a token's header and payload so it can't be tampered with. Plain explanation of HMAC vs RSA signatures with verification code.
What Is Localhost? (127.0.0.1, ::1, and Why It Matters)
Localhost is your computer talking to itself — the network address 127.0.0.1 (IPv4) or ::1 (IPv6) that loops back to the same machine. Plain explanation with use cases.
What Is a MIME Type? (Content-Type Headers Explained)
A MIME type is a label that tells software what kind of data a file or HTTP response contains — like application/json or image/png. Plain explanation with examples.
What Is OAuth? How "Sign In With Google" Actually Works
OAuth is the industry-standard protocol that lets you grant one app limited access to your data on another, without giving it your password. Clear walkthrough of OAuth 2.0 flows.
What Is Same-Origin Policy? (Web Security 101)
Same-origin policy is the browser security rule that prevents JavaScript on one site from reading data from another. Plain explanation of origins and exemptions like CORS.
What Is UTF-16? (Java, JavaScript, Windows Use It)
UTF-16 encodes Unicode using 16-bit code units (2 or 4 bytes per character). Native to JavaScript strings, Java, and Windows APIs. Plain explanation of surrogate pairs.
What Is a Webhook? Clear Explanation + When to Use One
A webhook is a reverse API: instead of you calling a server, the server calls your URL when something happens. Plain-English explanation with examples and security tips.
What Is a WebSocket? Real-Time Two-Way Web Connections
A WebSocket is a persistent two-way connection between browser and server that stays open for instant messaging, live updates, and multiplayer features. Clear explanation with use cases.
What Is XPath? Querying XML and HTML Documents
XPath is a query language for selecting nodes in XML and HTML — like CSS selectors but more powerful. Plain explanation with practical examples for scraping and testing.
Want to try the concepts?
Every glossary entry links to the Utilko tools that let you experiment with the concept — generate a UUID, decode a JWT, hash a string, look up an IP.
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