The Writing Centre has compiled a list of websites for students who are struggling with grammar. These websites provide students with information ranging from definitions and examples of parts of speech to practical advice on the writing process; sentence and paragraph construction and so forth. Most of the websites have interactive exercises that are useful for students wanting to practice their grammar skills.
Purdue Online Writing Lab [broken link] offers help with grammar issues such as sentence structure, verbs, adjectives, pronouns etc. It also looks at punctuation - apostrophe, comma, hyphen and quotation marks. Within the arena of spelling, sound-alike words, plurals and suffixes are discussed prior to the offered self-testing exercises in the three areas covered.
Guide to Grammar and Style deals mainly with grammatical rules and usage. A good site as it offers interactive exercises and experiments with language.
Daily Grammar is a free service that offers daily lessons which can be completed at one's own pace.
English Club is especially designed for ESL learners. It offers ESL Games, Software, eBooks and links to sites like TEFLGames.com.
Garbl's Writing Centre advises on the writing process as well as grammar and punctuation. The punctuation section is particularly useful for students who are struggling in this area.
11 Rules of Writing is a concise guide to some of the most commonly violated rules of writing, grammar and punctuation. It aids in the learning and refining of writing.
HyperGrammar looks at the micro-level of writing detailing parts of speech, sentence building, phrases, paragraphs and other aspects of grammar.
Online English Grammar [broken link] is an A-Z catalogue that covers grammar from its foundations to its more complex components.