A plain text file (.txt) is a simple, unformatted document that contains only text characters, adhering to a character encoding standard such as ASCII, UTF-8, or UTF-16. It lacks any specific formatting, such as bolding, italics, font styles, or embedded images. Plain text files are highly portable and can be opened and edited by virtually any text editor or word processor on any operating system. They are commonly used for storing configuration files, source code, simple notes, log files, and other data where formatting is not essential. The simplicity of the format ensures compatibility across different platforms and software applications. Because they contain only text, they are also relatively small in size compared to formatted documents. Plain text files are often used as a base format for more complex file types, with additional formatting or metadata added on top. They are a fundamental building block in computing and data storage.