A directory is a list of links based on categories and subcategories. They were featured prominently in the early days of the Web and were used for link acquisition. Each directory had different requirements for inclusion, which ranged from free submission to paid submission and human curation. Although many of the old, popular directories have since waned, directories, in general, remain popular in certain markets. Some examples of directories are Yahoo! Directory, DMOZ and Best of the Web, as well as hao123.com in China.