If you're trying to improve your writing, a natural starting-point is to learn more about the language we all share. Language is the medium the writer uses, just as charcoal, oil paints and watercolours are the media the artist uses. If I wanted to improve my painting or drawing, I'd probably look into what's known about these media and how to use them more effectively.
My aim is to introduce and explain how to use the grammatical terms 'noun', 'verb', 'preposition', and so on - the so-called Parts of Speech - that you're likely to come across if you read about writing skills. I'll do this assuming almost no background in grammar, but will try to mix explanations through simple examples with at least some indications of how a more rigorous theory can be developed.
I'm writing this partly because I've found that so many of the accounts in English textbooks and other books for the general reader are confusing and inaccurate.