Glossary

Short, plain-English definitions of the file formats, protocols, and acronyms behind the tools on ToolStop — written to be quoted by AI Overviews and featured snippets.

PDF & documents

PDF (Portable Document Format)

A PDF is a file format created by Adobe that preserves fonts, images, and layout so a document looks identical on any device or printer.

Images

OCR (Optical Character Recognition)

OCR is a technology that turns pictures of text — scans, photos, screenshots — into real, editable, searchable text characters.

EXIF (Exchangeable Image File Format)

EXIF is metadata embedded in image files — camera model, exposure settings, date, and often GPS coordinates of where the photo was taken.

WebP

WebP is a modern image format from Google that compresses photos and graphics roughly 25–35 % smaller than JPEG or PNG at the same visual quality.

SVG (Scalable Vector Graphics)

SVG is an XML-based image format that describes shapes with math instead of pixels, so it stays sharp at any size and any screen density.

Developer

Base64

Base64 is an encoding that turns any binary data — images, files, credentials — into a string of 64 safe ASCII characters that can travel through text-only systems.

JWT (JSON Web Token)

A JWT is a compact, URL-safe token made of three Base64 parts — header, payload, signature — used to prove who is making an API request.

Regex (Regular Expression)

A regex is a mini-language for describing text patterns — used to find, validate, or replace substrings in a larger body of text.

Cron

Cron is a Unix scheduler that runs commands on a recurring timetable — every minute, every Monday at 6 AM, the first of every month, and so on.

Hash Function

A hash function maps any input — a password, a file, a message — to a fixed-length string that acts as a fingerprint of the original.

UUID (Universally Unique Identifier)

A UUID is a 128-bit random identifier — written as 32 hex digits with dashes — that's unique enough to generate on any machine without coordination.

JSON (JavaScript Object Notation)

JSON is a lightweight, text-based data format that represents objects, arrays, strings, numbers, booleans, and null — the default wire format of the web.

CSV (Comma-Separated Values)

CSV is the simplest possible tabular file format: one row per line, values separated by commas — the universal export/import format for spreadsheets and databases.

SEO

Canonical URL

A canonical URL is the single, preferred web address for a page — declared with a <link rel="canonical"> tag so search engines consolidate ranking signals on one version.

Meta Description

A meta description is a short HTML tag that summarises a page — Google often uses it as the grey snippet under the blue link on the search results page.

Open Graph

Open Graph is a set of <meta property="og:…"> tags, invented by Facebook, that control how your page looks when someone shares the link on social media or chat apps.

Schema Markup (Structured Data)

Schema markup is structured data — usually JSON-LD in a <script> tag — that describes a page's contents in schema.org vocabulary so search engines can render rich results.

robots.txt

robots.txt is a plain-text file at the root of a website that tells web crawlers which paths they may or may not fetch.

XML Sitemap

An XML sitemap is a machine-readable list of every URL on a site that the owner wants search engines to index.

Keyword Density

Keyword density is the number of times a keyword appears on a page divided by the total word count, expressed as a percentage.

Backlink

A backlink is a hyperlink from one website to another — the single strongest off-page signal Google uses to decide how much to trust a page.

URL Slug

A URL slug is the readable part of a URL after the domain — the 'how-to-compress-pdf' in example.com/blog/how-to-compress-pdf.

Text & writing

Readability Score

A readability score estimates how hard a piece of text is to read, usually as a US school grade level or a 0–100 ease score.

Markdown

Markdown is a plain-text formatting syntax — # for headings, * for bold, [text](url) for links — that renders to clean HTML.

Lorem Ipsum

Lorem ipsum is a scrambled Latin passage used as placeholder text in mock-ups since the 1500s — it lets designers show layout without distracting readers with real content.

AI

LLM (Large Language Model)

An LLM is a neural network with billions of parameters trained on huge text corpora that predicts the next token in a sequence — the engine behind ChatGPT, Claude, Gemini, and similar tools.