Online companies that offer expert answers to questions of various categories include AllExperts and Simply Explained. Other sites host experts from specific fields, including JustAnswer and Experts Exchange.
These sites require experts to have either some experience in the field to which they've applied or an above-average knowledge of the subject. As a result, these companies require registration from those who answer questions on these sites. General question sites, such as AllExperts and Simply Explained, have experts in business, technology, food, music, sports and travel, among other categories. JustAnswer.com hosts legal, home and health experts, including lawyers, mechanics and doctors. Experts Exchange has experts dedicated to technology-based questions and issues.