What are the options for inviting a friend for a long stay in Thailand?

To invite a friend for a long stay in Thailand, different visa options exist depending on your nationality and personal situation. Commonly suggested choices include a tourist visa for 60 days with a possible 30-day extension, enrolling in an approved educational institution for an ED visa, or applying for a non-immigrant visa such as a type-B (if employed with a work permit) or type-O (which can be based on marriage to a Thai national or retirement at age 50 with proof of funds). For younger individuals not meeting these criteria, the Thai Elite Visa is another option.