Perform and preform are easily confused words.
The spell-check application of most word processing software programs would not catch a slip-up of these two words. Spell-check is looking for words that aren’t in its dictionary, and words that resemble words in its dictionary but are possibly spelled wrong. Spell-check isn’t perfect. It doesn’t know and can’t guess what word you wanted or what word you meant, it can only judge the words on the page. If you used words that are all spelled correctly, it gives you a pass anyway.
Autocorrect suggests words that start with the same letters. It’s suggesting what word you may want to save time, but quite often, its suggestions are pretty off base. They don’t help you out, but they do make you laugh.
Perform (pronounced “purr-fohrrmm”) is a verb. It means to showcase talents on a stage, for example, acting, singing, dancing, or dramatic reading. It can also mean to execute the numbered steps of a procedure or a list of tasks.
Preform (pronounced “pree-fohrr-mm”) is a verb. It means an object that is molded or shaped before it is used or incorporated into something else.
The following story uses both words correctly:
Perfidia was working at her manfacturing job, making preformed plastics, when she got the call that she needed to perform as the lead in tonight’s production of Sweeney Todd. The regular star had had a car accident, so Perfidia, as understudy, had to take her place.