.ac:  .ac is the domain name of Ascension Island, located in the West Ocean, the colony of UK, for .ac is considered as the abbreviation of “academic”, it is so popular in UK, United States, Australia and Japan, .ac enters the domain market as a new member now, so there are so many domain names for your choice,such as Beijing .ac，Shanghai .ac, Guangdong .ac etc. With the particular meaning of academic, it is the best choice for academia.