Computer file

Computer file

Filename extension	Various
Internet media type
Uniform Type Identifier (UTI)
Magic number
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Type of format
Container for
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A computer file is a digital resource for storing information, which is available to a computer program and is usually based on some kind of durable storage. A file is "durable" in the sense that it remains available for programs to use after the current program has finished.

Structure

A computer file is typically organized in a hierarchical structure, which includes the following components:

File Name

The file name is a string of characters that uniquely identifies a file within a directory. It often includes an extension that indicates the file type, such as `.txt` for text files or `.jpg` for image files.

File Extension

A file extension is a suffix at the end of a file name that indicates the file's format or type. For example, `.docx` indicates a Microsoft Word document, while `.mp3` indicates an audio file.

File Path

The file path is a string that specifies the location of a file within a file system. It includes the directory and subdirectory names leading to the file.

File Metadata

Metadata is data about data. In the context of files, metadata includes information such as the file's size, creation date, modification date, and permissions.

Types of Files

Files can be broadly categorized into several types based on their content and usage:

Text Files

Text files contain human-readable characters and are often used for storing written content. Examples include `.txt`, `.csv`, and `.html` files.

Binary Files

Binary files contain data in a format that is not human-readable. They are used for storing images, audio, video, and executable programs. Examples include `.exe`, `.jpg`, and `.mp4` files.

Executable Files

Executable files contain programs that can be run by the computer. They include files with extensions like `.exe` on Windows or `.sh` on Unix-based systems.

File Systems

A file system is a method and data structure that an operating system uses to control how data is stored and retrieved. Without a file system, data placed in a storage medium would be one large body of data with no way to tell where one piece of data stops and the next begins.

Common File Systems

• FAT32
• NTFS
• ext4
• HFS+

File Operations

Common operations that can be performed on files include:

Creating

Creating a file involves allocating space in the file system and assigning a name to the file.

Reading

Reading a file involves accessing the data stored in the file and interpreting it according to the file format.

Writing

Writing to a file involves modifying the data stored in the file or appending new data to it.

Deleting

Deleting a file involves removing its entry from the file system, which may also free up the space it occupied.

Security and Permissions

File security is crucial to protect sensitive data from unauthorized access. File permissions determine who can read, write, or execute a file. Common permission settings include:

• Read (r)
• Write (w)
• Execute (x)

Also see

• File system
• File format
• Data storage device
• Operating system