Glossary

Short definitions of the terms you'll hit while wrangling JSON, XML, and HTML. If a term is missing and you think it belongs, let us know via the contact page.

B

• Beautify — A near-synonym for pretty-print, often used in tool names and UI labels to describe making code readable.
• BOM — Byte Order Mark — an invisible character at the start of a text file that signals encoding and endianness.
• BSON — Binary JSON — MongoDB's on-disk and wire format that extends JSON with types like Date, Binary, and 64-bit integers.

C

• CDATA — A section of an XML document where markup characters are treated as plain text, letting you embed code or HTML snippets without escaping.

D

• DOCTYPE — The document type declaration at the top of an HTML or XML document that tells the parser which rules to apply.
• DTD — Document Type Definition — the original XML schema language, inherited from SGML, still encountered in legacy documents.

E

• Entity — A named or numeric reference in HTML or XML that stands in for a single character, like & for ampersand.
• Escape Sequence — A character or group of characters that represent a special character inside a string literal.

H

• HTML — HyperText Markup Language — the text-based markup language that defines web pages.
• HTML5 — The major version of HTML that replaced the XHTML line and introduced a Living Standard maintained by WHATWG.

J

• JSON — JavaScript Object Notation — the text-based data format standardised in RFC 8259 and ECMA-404, used as the default wire format for modern web APIs.
• JSON Patch — A format for describing changes to a JSON document as a list of operations, defined in RFC 6902.
• JSON Pointer — A standard syntax for addressing a specific value inside a JSON document, defined in RFC 6901.
• JSON Schema — A JSON-based vocabulary for describing, documenting, and validating the shape of JSON documents.
• JSON-LD — JSON for Linked Data — a method of encoding semantic-web and schema.org metadata inside ordinary-looking JSON.
• JSONC — JSON with Comments — a superset used by VS Code and the TypeScript ecosystem that allows `//` and `/* */` style comments.
• JSONL — JSON Lines — a format where each line of a file is a complete JSON document, typically a single object.
• JSONP — JSON with Padding — a pre-CORS workaround for cross-origin requests, now obsolete in modern web development.

M

• Minify — The process of stripping whitespace, comments, and other optional characters to reduce the byte size of a document.

N

• NDJSON — Newline-Delimited JSON — a nearly-identical sibling of JSONL used interchangeably in most toolchains.

P

• Parser — A program that reads a sequence of bytes or tokens and produces a structured representation (usually a tree or in-memory value).
• Pretty-Print — The process of formatting data — typically JSON, XML, or HTML — with line breaks and indentation for human reading.

U

• UTF-8 — The dominant character encoding on the modern web — variable-width, backward-compatible with ASCII, and the default for JSON.

V

• Validator — A tool that checks whether a document conforms to a syntax or schema, and reports any violations.
• Void Element — An HTML element that has no closing tag and no content, such as <br>, <img>, and <meta>.

X

• XML — eXtensible Markup Language — a text-based markup format for structured documents, standardised by the W3C in 1998.
• XML Namespace — A mechanism for mixing elements from different vocabularies in a single XML document without name collisions.
• XPath — A path-based query language for selecting nodes from an XML document, standardised by the W3C.
• XSD — XML Schema Definition — the W3C standard for describing and validating the shape of XML documents.
• XSLT — eXtensible Stylesheet Language Transformations — a declarative language for transforming XML documents into other XML, HTML, or text.