Text file in the context of Microsoft Windows

A file format is the way that information is encoded for storage in a computer file. It may describe the encoding at various levels of abstraction including low-level bit and byte layout as well high-level organization such as markup and tabular structure. A file format may be standarized (which can be proprietary or open) or it can be an ad hoc convention.

Some file formats are designed for very particular types of data: PNG files, for example, store bitmapped images using lossless data compression. Other file formats, however, are designed for storage of several different types of data: the Ogg format can act as a container for different types of multimedia including any combination of audio and video, with or without text (such as subtitles), and metadata. A text file can contain any stream of characters, including possible control characters, and is encoded in one of various character encoding schemes. Some file formats, such as HTML, scalable vector graphics, and the source code of computer software are text files with defined syntaxes that allow them to be used for specific purposes.

The syntax of computer source code is code structured and ordered restricted to computer language rules. Like a natural language, a computer language (i.e. a programming language) defines the syntax that is valid for that language. A syntax error occurs when syntactically invalid source code is processed by an tool such as a compiler or interpreter.

The most commonly used languages are text-based with syntax based on strings. Alternatively, the syntax of a visual programming language is based on relationships between graphical elements.

In software, a spell checker (or spelling checker or spell check) is a software feature that checks for misspellings in a text. Spell-checking features are often embedded in software or services, such as a word processor, email client, electronic dictionary, or search engine.

In computing, a delimiter is a character or a sequence of characters for specifying the boundary between separate, independent regions in data such as a text file or data stream. For context, data boundaries can be indicated via other means. For example, declarative notation indicates the length of a field at the start of the field instead of relying on delimiters.

In mathematics, delimiters are often used to specify the scope of an operation in an expression, and can occur both as isolated symbols (e.g., colon in "${\displaystyle 1:4}$") and as a pair of opposing-looking symbols (e.g., angled brackets in ${\displaystyle \langle a,b\rangle }$).

A binary file is a computer file that is not a text file. The term "binary file" is often used as a term meaning "non-text file". Many binary file formats contain parts that can be interpreted as text; for example, some computer document files containing formatted text, such as older Microsoft Word document files, contain the text of the document but also contain formatting information in binary form.

Lempel–Ziv–Welch (LZW) is a universal lossless compression algorithm created by Abraham Lempel, Jacob Ziv, and Terry Welch. It was published by Welch in 1984 as an improvement to the LZ78 algorithm published by Lempel and Ziv in 1978. Claimed advantages include: simple to implement and the potential for high throughput in a hardware implementation.

A large English text file can typically be compressed via LZW to about half its original size.

In the Warez scene, .nfo (short for info) is a file name extension for a text file (sometimes called an NFO file) that accompanies and describes a release of pirated software or media. The file contains information such as title, authorship, year and license information. For software, it might contain installation notes. This information is delivered for publishing through digital media to make it searchable on the web as well as within local catalogues and libraries. This type of file is also often found in a demoscene production, where the respective group includes it for credits, contact details, and the software requirements.

This type of file has been described as the press release of the warez scene. Info files were ubiquitous, and sometimes required, during the era of the Bulletin Board System (BBS). The file was a stamp of authenticity, explicitly explaining what group released the software and described what modifications (or cracks) were applied if any. Once a software was packaged with an info file and then released, it was then officially owned by that group and no other group could ethically re-release that particular package. A typical warez info file was elaborate and highly decorated, and usually included a large ASCII art logo along with software release and extended warez group information. The most important information is which group, which cracker and which member actually tested and packaged. The designers of these info files, who worked closely or within the warez groups, frequently incorporated extended ASCII characters from the character set code page 437 in the file.

A document file format is a text or binary file format for storing documents on a storage media, especially for use by computers.There currently exists a multitude of incompatible document file formats.

Examples of XML-based open standards are the ISO/IEC standards OpenDocument (ISO 26300:2006) and the Strict and Transitional versions of Office Open XML (ISO 29500:2008). Another example is DocBook which is used for writing structured documentation such as manuals, books, technical guides, and then processed with stylesheets/toolchains to generate HTML, PDF, EPUB, man pages, etc. XHTML, an earlier document file format over time became part of HTML5.