Typo is short for typographical error. On your page or screen, you have two different typo opportunities: the words, and the rest.
Checking your words
The spellchecker option within word-processing can give the impression that you have no mistakes in your words. If there are no red squiggly lines, then all is well? No!
You get the idea! The wrong word can still pass muster for the spellchecker.
Even if every word is correctly spelt, you might have missed out a word altogether. You might have used capital letters incorrectly!
The only way to find all these typos is to proofread (aloud preferably) what you have written. Or ask someone else to do this for you.
And what’s ‘the rest’? The rest is your punctuation and spacing.
What is punctuation?
Punctuation is any symbol used to ‘punctuate’ your words: correctly used, punctuation makes the sense clearer to your reader.
What are the ‘rules’ for spacing?
BEWARE: the act of editing can introduce more typos. Every time you make changes to your writing, proofread it again.