A TXT file is a plain text file: a sequence of characters and nothing else. There are no fonts, sizes or colours, no bold or italics, no images or tables. Line breaks are the only structure it has. The .txt extension is a convention rather than a format owned by anyone, and that simplicity is its strength: a text file written decades ago opens today on any computer, phone or server, in any editor.
Characters and encodings
A computer stores text as numbers, and an encoding is the table that says which number means which character. A TXT file does not say which table was used, and that is the source of nearly every problem with plain text.
- ASCII covers 128 characters: the English alphabet, digits and basic punctuation. Every common encoding agrees on these.
- Windows-1252 and ISO 8859-1 (Latin-1) add Western European letters such as é, ü and ñ, one byte each.
- UTF-8 encodes all of Unicode, every script and symbol including emoji, and is compatible with ASCII. It is the standard encoding of the web and the safe choice for any new file.
When a file is read with the wrong table, letters outside ASCII come out as gibberish. The classic sign is café appearing as café: UTF-8 bytes read as if they were Windows-1252. Some editors write a byte order mark, a few invisible bytes at the start of the file, to announce UTF-8; others do not, and most programs guess correctly either way.
Line endings
Text files mark the end of a line differently depending on where they were made. Windows uses two characters, carriage return and line feed (CR LF); Linux and macOS use a line feed (LF) alone. Modern editors handle both, but an older program may show a file from another system as one endless line, or with stray symbols at every line end.
When plain text is the right format
- Notes, drafts and to-do lists that you want to open anywhere, forever.
- Text you will paste into other places, such as a website, an email or a form, where hidden formatting would get in the way.
- Configuration files, logs, data exports and anything a program has to read.
- Writing that will be formatted later. Markdown is plain text with a few symbols for headings and emphasis, for when you want some structure without leaving plain text behind.
One trap on a Mac: TextEdit opens TXT files fine, but saves new documents as RTF by default. Choose Format > Make Plain Text before saving to get a real TXT file.
How the spell checker helps
Plain text is the most direct way into the Spell Checker: open a TXT file and its text goes straight into the editor, with no formatting to get in the way. Check it for spelling, grammar and punctuation (and style, with Picky mode), apply the fixes, and download the corrected text as TXT again, or as DOCX, ODT, RTF, HTML, Markdown or PDF if it needs to become a formatted document. It reads UTF-8 and UTF-16 files, and falls back to Windows-1252, the encoding older Windows programs wrote, so most files open as they should; if letters still look wrong, the file uses another encoding: save it as UTF-8 in your editor and open it again. A single check covers a whole document of up to 150,000 characters.