---
source: https://csrc.nist.gov/glossary/term/file
title: "A computer file is a named collection of information"
license: CC-BY-4.0
license_url: https://creativecommons.org/licenses/by/4.0/
source_license: "public domain (US government work): NIST CSRC glossary; W3C Software and Document License (File API)"
attribution: "Summary by iinventedlight (AI-assisted). Sources: NIST CSRC glossary, public domain (US government work); File API, W3C Software and Document License. This document includes material copied from or derived from File API https://www.w3.org/TR/FileAPI/. Copyright © 2026 World Wide Web Consortium. https://www.w3.org/copyright/software-license-2023/"
author: "iinventedlight (synthesis of cited sources); text drafted with AI assistance"
date: 2026-11-11
status: published
approved_by: "Cole Withington, 2026-11-11 18:00 PT, Librarian chat widget t46s287: \"Publish all 11, but put the full notice into the 2 spec notes first\""
checked_on: 2026-11-11
as_of: 2026-11-11
confidence: high
untested: "No operating system was run; claims restate the NIST glossary definition and the W3C File API."
category: science
topic_area: "science: computer file"
tags: [science, computing, files, nist, file-api]
client: Librarian
sources:
  - id: S1
    title: "File (CSRC Glossary)"
    publisher: "NIST Computer Security Resource Center"
    url: https://csrc.nist.gov/glossary/term/file
    accessed: 2026-11-11
    license: "public domain (US government work)" 
  - id: S2
    title: "File API"
    publisher: "W3C"
    url: https://www.w3.org/TR/FileAPI/
    accessed: 2026-11-11
    license: "W3C Software and Document License" 
---
# A computer file is a named collection of information

**Answer:** A file is information grouped as one entity and referred to by a unique name, such as a filename. On the web, a `File` object is a `Blob` with a name, and it often refers to bytes from the underlying operating-system file system.

## The NIST definition

The NIST CSRC glossary, citing NIST SP 800-86, defines a file as information grouped as one entity and referred to by a unique name, such as a filename.

## Files in web applications

The W3C File API represents file objects in web applications so a program can select them and read their data. A `File` interface includes read-only attributes about a file, such as its name and the date of last modification on disk.

The spec says a `File` object is a `Blob` with a name attribute. The name is a string. The object can be created via a constructor, or it is a reference to a byte sequence from a file on the underlying file system. The File interface represents file data typically obtained from that file system.



## Claims

- id: C1
  claim: NIST defines a file as a named collection of information grouped as one entity.
  source: S1
  evidence: "A collection of information logically grouped into a single entity"

- id: C2
  claim: A File object is a Blob with a name attribute.
  source: S2
  evidence: "A File object is a Blob object with a name attribute"

- id: C3
  claim: The File interface includes a file's name and last-modification date.
  source: S2
  evidence: "attributes about a file such as its name"

## Sources

- [S1] File (CSRC Glossary). NIST Computer Security Resource Center. https://csrc.nist.gov/glossary/term/file . License: public domain (US government work). Accessed 2026-11-11.

- [S2] File API. W3C. https://www.w3.org/TR/FileAPI/ . License: W3C Software and Document License. Accessed 2026-11-11.