Learning English as a Second Language (ESL) is a difficult and frustrating endeavor for many people around the world. Besides studying endless vocabulary lists, common idioms and pronunciation and intonation skills, ESL students have to master English grammar. There are several websites that offer free lessons to aid in this challenging pursuit

Dave's ESL Cafe
This is a well-known website for ESL students and teachers alike. The grammar portion of this site offers lessons that cover numerous parts of speech, spelling rules and nuances, and special expressions. Other useful sections pay close attention to conversational grammar and confusing words.

ESL Gold
This website categorizes its grammar lessons into sections specifically designed for various levels, and in an easy-to-access manner. Lessons range from low-beginner levels to high-advanced sections, and it offers grammar explanations and exercises ranging from adverbs to verb and preposition collocations. The site also offers other sections including reading, writing, comprehension lessons and exercises in addition to links to various other ESL resources and books.

EnglishClub
There are many grammar explanations and lessons on this site as well as quizzes so students can follow up and check their comprehension and skill acquisition. Students who are stumped on a given lesson or quiz can also access and ask questions via a Grammar Help Desk on the site. Students can get answers to their questions and difficult concepts from site moderators.

English Page
This site separates its lessons into various parts of speech sections, including phrasal verbs, prepositions, gerunds and verb tenses. ESL students and professionals are encouraged to recommend favorite, related sites as well as add material and lessons to its "English Grammar Book" and related links.

Guide to Grammar and Writing
This site is sponsored by the Capital Community College Foundation, and offers numerous grammar lessons and quizzes. Other lessons that focus on essay and research writing in addition to sentence and paragraph writing tips are also available at no charge. Many other resources are categorized and ready to access on this site.