Developer Glossary

Short, plain-English answers to the questions you Google more than you'd like to admit.

Encoding

Base64

Base64 encodes any binary data, images, files, secrets, as a string of letters, digits, +, /, and =.

URL encoding

Replacing unsafe characters in a URL with a % followed by their hex byte, so spaces, & and ? don't break the URL.

HTML entities

Escape codes like `&` and `<` that let you show `<` and `&` as text without breaking the markup.

ASCII

The original 128-character set: A–Z, a–z, 0–9, punctuation, and control codes. The foundation every modern encoding builds on.

UTF-8

The default text encoding of the modern web, encodes every Unicode character in 1–4 bytes.

Data & IDs

UUID

A 128-bit ID, written as 36 characters, that's unique enough to use anywhere without coordinating with anyone.

UUID v4

The 'random' UUID, generated from 122 random bits, with collisions effectively impossible.

UUID v7

A time-ordered UUID, sorts by creation time, so it plays nicely with database indexes.

Nano ID

A shorter, URL-friendly alternative to UUIDs, same collision safety, fewer characters.

Regex

A mini-language for describing patterns in text, used to find, validate, or replace strings.

Data Formats

JSON

A lightweight text format for sending structured data, the lingua franca of web APIs.

YAML

A human-friendly data format used in config files, same data model as JSON, but indented and with comments.

TOML

A config format that's strict enough to parse unambiguously and friendly enough to read.

CSV

A plain-text table: one row per line, fields separated by commas. The lowest-common-denominator data format.

XML

A tag-based data format, like HTML, but you invent the tags. Verbose but extremely well-supported.

Security

JWT

A signed token (three dot-separated Base64 chunks) that lets a server trust a client's identity without a session lookup.

Hash function

A one-way function that turns any input into a fixed-size fingerprint, the same input always produces the same hash.

HMAC

A hash plus a shared secret, proves a message came from someone who knows the secret AND wasn't tampered with.

bcrypt

A slow-by-design password hash, the slowness is what protects your users from brute force.

Salt

Random bytes mixed into a password before hashing, so the same password gets a different hash for every user.

Web Basics

HTTP status code

A 3-digit code in every HTTP response that says whether the request succeeded, `200 OK`, `404 Not Found`, `500 Server Error`.

HTML

The markup language that gives every web page its structure, headings, paragraphs, links, images, the whole skeleton.

Dates & Time

Unix timestamp

The number of seconds (or milliseconds) since January 1, 1970 UTC, the time format computers use under the hood.

ISO 8601

The international date format: `YYYY-MM-DDTHH:MM:SSZ`. Unambiguous, sortable as text, supported everywhere.

Cron expression

Five fields, minute, hour, day, month, weekday, that describe when a job should run.