Spell checkers are all well and good but they won't pick up subtleties in the language such as the difference between 'your' and 'you're' and 'there' 'their' and 'they're' all of which are correct spellings but are so often used incorrectly on these pages. Simple fact is there's no substitute for a bit of education. There are also books with words in called 'Dictionaries' which are freely available at most good bookshops.