Getting quick answers to grammar-related questions can be a challenge. Here’s a great free online resource called Common Errors in English Usage by Paul Brians. Brians is an Emeritus Professor of English at Washington State University.
Many grammar guides offer lengthy convoluted descriptions of grammar rules. I especially like this one because of its practical nature. If you have a question about, say, using semicolons, use the search engine or click the letter “S” and you’ll find a concise explanation of how and when to use semicolons.
This is a helpful link for times when grammar questions arise. Near the bottom of the home page are links to additional online grammar resources recommended by the author.