This book does two things. It gives you the forty rules that are worth the memory - far more than most people expect, and far fewer than any school taught - and then it gives you the words that break them, because a rule you cannot trust is worse than no rule at all. Every entry shows the rule, the condition it depends on, the words that follow it, and the misspellings people actually write.
Six parts: the four rules worth memorising, what happens when you add an ending, the unstressed vowels that cause more errors than anything else, doubles and silent letters, prefixes and borrowed words, and the British and American split.
The last of those is handled as two correct national standards rather than a right and a wrong. Color is no more an error in Ohio than colour is in Leeds; the only real mistake is mixing them in one document. With the five core rules and all their exceptions on one page at the back, and the hundred hardest words on another.
Alex Carter writes practical English books for people who use the language at work and in ordinary life rather than in a classroom. The books are built around complete examples — real emails, real conversations, real sentences — on the principle that one worked example teaches more than a page of rules.