Domain extensions are generally categorised into Global/Generic TLDs (gTLDs), Country Code TLDs (ccTLDs) and recently released new domain extensions TLDs (nTLDs).
Generic TLDs or gTLDs such as .com, .net, .org, .info also called a legacy TLDs.
Country Code TLDs or ccTLDs are domain extensions that are based on the country or region. For example .co.id for Indonesia, .com.au for Australia, .us for United States, .eu for European Union and etc.
New Domain Extensions or nTLDs are domain extensions with a more memorable, meaningful and specific towards certain keywords and businesses. They were recently released in year 2014 and we will continue to have the new release in stages for the next few years.