This book was written for those who already have some knowledge of English and want to improve. It was written especially for ESL students and uses English words that are similar to the same word in Spanish whenever possible. It also tries to educate the reader about a variety of subjects whenever possible.
The sentences are short and informal. "Confusing Words" includes when to use fewer and less, bring and take, may and can, lend and borrow, and farther and further, to list a few. It also lists some common homophones--words that sound alike. Heteronyms are words that look alike but may be pronounced differently, like present, record, and wound.