This is a ‘lazy’ post as it’s a direct lift from a BBC web-page.
My added value is editorial selection: one web-page from many; and one short extract from a longer piece on grammar. I particularly enjoyed the following take on the split infinitive, as summed up in 1926 by Henry Fowler, author of the Dictionary of Modern English Usage:
The English-speaking world may be divided into:
1. Those who neither know nor care what a split infinitive is.
2. Those who do not know, but care very much.
3. Those who know and condemn.
4. Those who know and approve.
5. Those who know and distinguish.
Those who neither know nor care are the vast majority, and are a happy folk, to be envied by the minority classes.