English
Trace standards, evidence, and implementation.
This site helps you check web standards (published rules for web technologies), their sources, how browsers behave, and how they share information with screen readers and other tools people use to access the web. Each page shows what has been checked and what still needs investigation.
EVIDENCE MODEL
Read normative claims separately from implementation
Each topic separates normative claims from observations made in browsers or accessibility trees. Unrun items are not treated as reviewed.
- SPEC — A claim checked against a standard
- IMPL — An implementation observation reproduced in a browser
- WPT — A Web Platform Tests mapping and execution result
- AAM — An accessibility-tree or assistive-technology observation
HTML topics
- HTML / ElementThe <article> Element — Independent Content, Nesting, and Accessibility Mapping
- HTML / ElementThe <nav> Element — Navigation Sections, Landmark Names, and Multiple Areas
- HTML / ElementThe <section> Element — Sectioning Content, Headings, and Region Mapping
- HTML / ElementThe <h1>–<h6> Elements — Heading Levels, Outline, and Accessibility
- HTML / ElementThe <main> Element — Primary Content, Placement, and the Main Landmark
- HTML / ElementThe <caption> Element — Table Names, Content Model, and Accessibility
- HTML / ElementThe <th> Element — Header Cells, scope, headers, and Accessibility
- HTML / ElementThe <td> Element — Data Cells, headers, the Table Model, and Accessibility
- HTML / ElementThe <tr> Element — Rows, Row Indexes, and Accessibility
- HTML / ElementThe <thead> Element — Header Row Group, DOM APIs, and Accessibility
- HTML / ElementThe <tbody> Element — Row Groups, DOM APIs, and Accessibility
- HTML / ElementThe <canvas> Element — Bitmap, Context, Fallback, and Origin-clean
- HTML / ElementThe <source> Element — Resource Selection, Attributes, and Fallback
- HTML / ElementThe <video> Element — Media Resources, Playback State, Text Tracks, and Accessibility
- HTML / ElementThe <track> Element — Text Tracks, Captions, WebVTT, and Accessibility
- HTML / ElementThe <audio> Element — Media Resources, Playback State, and Accessibility
- HTML / ElementThe <picture> Element — Source Selection, Art Direction, and Fallback
- HTML / ElementThe <img> Element — Alt Text, Image Selection, and Loading
- HTML / Image mapsImage maps — <map>, <area>, and <img usemap>
- HTML / ElementThe <meter> Element — Gauge Semantics, Ranges, and Accessibility
- HTML / ElementThe <progress> Element — Progress Values, Determinate State, and Accessibility
- HTML / ElementThe <template> Element — Template Contents, DocumentFragment, and Declarative Shadow DOM
- HTML / ElementThe <output> Element — Calculation Results, Form Association, and Submission Boundaries
- HTML / ElementThe <iframe> Element — Content Navigables, Sandboxing, and Accessibility
- HTML / ElementThe <dialog> Element — Modality, Focus, Close Requests, and the Top Layer
- HTML / ElementThe <details> Element — Disclosure, Open State, and Exclusive Groups
- HTML / ElementThe <summary> Element — Details Association, Activation, and Accessibility
- HTML / ElementThe <optgroup> Element — Grouping, Label, and Disabled Boundary
- HTML / ElementThe <datalist> Element — Suggestions, Input Association, and Accessibility
- HTML / ElementThe <option> Element — Selectedness, Values, Submission, and Accessibility
- HTML / ElementThe <legend> Element — Fieldset Caption, Accessible Name, and Disabled Boundary
- HTML / ElementThe <fieldset> Element — Grouping, Disabled Propagation, and Accessible Name
- HTML / ElementThe <a> Element — Hyperlink Semantics, Conditions, and Processing
- HTML / ElementThe <button> Element — Type States, Form Processing, and Activation
- HTML / ElementThe <input> Element — Type States, Form Association, and Validation
- HTML / ElementThe <label> Element — Labelable Association, Activation, and Accessible Name
- HTML / ElementThe <form> Element — Form Owner, Submission, and Validation
- HTML / ElementThe <script> Element — Kinds, Timing, and Fetching
- HTML / ElementThe <link> Element — Link Types, Resource Processing, and APIs
- HTML / ElementThe <meta> Element — Metadata, Encodings, and Pragmas
- HTML / ElementThe <select> Element — Option Selection, Form Submission, and Validation
- HTML / ElementThe <selectedcontent> Element — Selected Option Copying and Update Rules
- HTML / ElementThe <textarea> Element — Multiline Input, Values, and Validation
- HTML / ElementThe <table> Element — Table Model, Parser Recovery, and Accessibility
- HTML / ElementThe <tfoot> Element — Row Groups, DOM APIs, and Accessibility
- HTML / ElementThe <colgroup> Element — Column Groups, span, Table Model, CSS, and Accessibility
- HTML / ElementThe <col> Element — Columns, span, CSS, and Accessibility
A beginner-friendly starting point
Start with clear explanations in Yugien, then move between Yugien and Atlas when you need conditions, evidence, or implementation differences.