Copyright protects original creative works and grants creators ownership rights over the use of their work. Copyright begins as soon as a work is fixed in a tangible form. Protection lasts for the life of the creator plus 70 years. Fair use allows limited use of copyrighted works for purposes such as criticism, commentary, teaching, or research. The four factors considered for fair use are the purpose and character of the use, nature of the work, amount used, and effect on the work's market value. Obtaining permission is required for uses beyond fair use. Works in the public domain can be used freely.