I used to write can not. But a website like grammarily correct it to cannot. I am confused which one to use?
According to Oxford Dictionaries, both of them are acceptable:
Both cannot and can not are acceptable spellings, but the first is much more usual. You would use can not when the ‘not’ forms part of another construction such as ‘not only’. For example:
- These green industries can not only create more jobs, but also promote sustainable development of the land.
I also found this post from Grammarly blog:
Can’t is a contraction of cannot, and as such it’s sometimes unsuitable for formal writing. In everyday writing and in speaking, it’s ubiquitous:
Cannot is better for formal writing.
Don’t use can not when you mean cannot. The only time you’re likely to see can not written as separate words is when the word “can” happens to precede some other phrase that happens to start with “not”