Guide
Language access and PDF accessibility glossary
Plain definitions for the terms that come up in language access and document accessibility.
Last reviewed October 20, 2026. General information for public agencies, not legal advice. Rules change, so check the sources below and ask your lawyer or civil rights office what applies to you.
These are plain definitions, not legal definitions. Where a term has a legal meaning, check the rule that applies to you.
Language access terms
- Language access
- Giving people who do not speak English well a real way to use a program, service or piece of information in a language they can use.
- Limited English proficient (LEP)
- A person who does not speak, read, write or understand English well enough to take part fully in a program or service, and who may need language help.
- Vital document
- A document that a person needs to get a service or benefit, or that carries important rights or duties, such as an application, a notice of rights or a consent form. What counts depends on the agency and the rules that apply.
- Translation and interpretation
- Translation changes written text from one language to another. Interpretation changes spoken words. They are different skills, and an agency usually needs both.
- Machine translation
- Translation done by a computer program. It is fast and cheap, and it can contain errors or lose meaning.
- Certified translation
- A translation that a qualified translator or translation company has signed to say it is complete and accurate. Machine translation is not certified.
- Plain language
- Writing that readers can understand the first time they read it. It makes both original and translated text easier to use.
PDF and document terms
- Tagged PDF
- A PDF with a hidden structure that labels each part of the page as a heading, paragraph, list, table or image, so assistive technology can read it correctly. A PDF with no tags is often just a picture of a page.
- Reading order
- The order in which a screen reader reads the content. It should match the order a sighted person would read the page.
- Alt text
- A short text description of an image, read aloud by a screen reader for people who cannot see it.
- Remediation
- Fixing a document that is not accessible: adding tags, setting the reading order, adding alt text and correcting the language, title and other properties.
- OCR (optical character recognition)
- Software that turns an image of text, such as a scanned page, into real text that can be selected, searched and read by a screen reader.
- Screen reader
- Software that reads what is on a screen aloud, or sends it to a braille display, used by many people who are blind or have low vision.
- Artifact
- Content in a PDF that is marked as decoration, such as a page number or a background shape, so a screen reader skips it.
- PDF/UA
- The international standard (ISO 14289) for accessible PDF. It describes how a PDF has to be built inside: tags, structure, reading order and alt text.
- veraPDF
- An open-source checker that tests whether a PDF file meets PDF standards, including PDF/UA. It can report failures, but it cannot judge whether alt text is any good.
Standards and rules
- WCAG 2.1 Level AA
- The Web Content Accessibility Guidelines, version 2.1, at conformance level AA. It is the standard the ADA Title II web rule adopts for state and local government websites and documents.
- ADA Title II
- The part of the Americans with Disabilities Act that covers state and local governments. The Department of Justice’s 2024 rule applies WCAG 2.1 AA to their web content and mobile apps.
- Section 504
- A section of the Rehabilitation Act that bans disability discrimination in programs that get federal funding. HHS has a web accessibility rule under it.
- Section 508
- A federal law that sets accessibility requirements for the technology that federal agencies buy and use. People often also use the term for accessibility checks in general.
- Title VI
- Title VI of the Civil Rights Act of 1964. It bans discrimination based on race, colour or national origin in programs that get federal funding. Agencies have long applied it to language access, and the federal guidance on that changed in 2025.
- VPAT
- A Voluntary Product Accessibility Template: a document in which a vendor reports how well its product meets accessibility criteria. Buyers often ask for one.