A keyword is the word or phrase someone types or says into a search engine, and the phrase a page is written to appear for. It can be one word, such as 'dentist', or a whole question. Choosing which keywords your pages should answer is the first decision in SEO, because everything else is built on it.
A keyword is not something you sprinkle into a page. Google reads whole sentences and understands that 'tow truck', 'towing service' and 'my car broke down who do I call' are the same need. The job is to pick the searches worth winning and write one page that genuinely answers each, not to repeat a phrase a set number of times.
