File Text ::.. A text file (sometimes spelled "textfile": an old alternate name is "flatfile") is a kind of computer file that is structured as a sequence of lines. A text file exists within a computer file system. The end of a text file is often denoted by placing one or more special characters, known as an end-of-file marker, after the last line in a text file. "Text file" refers to a type of container, while plain text refers to a type of content. Text files can contain plain text, but they are not limited to such.