Microsoft Notepad isn't considered among the top text editor programs, but it's certainly one of the oldest and most widely installed.
Microsoft first introduced Notepad in May 1983, presenting it as a stripped-down version of the widely used Microsoft Word. The new piece of software arrived with the ability to bold, underline, and italicize text, and over the years, it slowly gained more features while still keeping its stripped-down initial design intention. One of the most requested features for Notepad is spellcheck, and while that may seem like a feature that should have already been added many years ago, it was once, and appears to be still, a big selling point for Microsoft Word.
However, 41 years later, Microsoft has decided to add spell check to Notepad, as the new feature has seemingly been rolled to Windows 11 Notepad versions 11.2405.13.0 and later. The feature was first tested back in March and works as every other spell checker works. If the spell checker believes a word has been spelled incorrectly, it will highlight that word with a red line underneath it. Users can right-click on that word and navigate to the "Spelling" option, where they will be presented with a list of possible correctly spelled words.
Unfortunately, there is still a little bit of buffoonery with Notepad's spellcheck. There isn't a global spellcheck, meaning Notepad cannot scan the entire document for errors. Instead, users will have to go one by one.
Sigh.