spellchecking software

Spellchecking in word processing software is a virtual application. The software does not actually know if your word is spelt correctly, it merely compares the word you have typed with a list of words. If the word you have typed is not in the list, the program highlights it as if it is spelt incorrectly.
The effect of this is so convincing that we often complain when a typo is spotted by someone else ‘I checked it on the spellchecker’ but unfortunately, they are only virtually right!