A top-level domain is one, which is at the highest level of hierarchical domain name system of the internet. It is generally used or reserved for a specific purpose or industry. For example, country top-level domains are reserved for specific countries; generic top-level domains are reserved for specific purposes.
The commonest and most popular top-level domain is the .com domain. It is an open top-level domain that any individual or organization is allowed to register. It was originally meant for the use of profit-making businesses but nowadays, many other categories have opted for this top-level domain because it is popular and fashionable. Examples of websites that use the top-level domain include www.facebook.com, www.yahoo.com
Another generic top-level domain is the .coop top-level domain. This top-level domain is reserved for cooperative societies. Examples of websites in this domain include http://www.ica.coop and http://www.cdi.coop
Another generic top-level domain is the .org name. It also an open top-level domain that any individual or organization may register. It is meant for non-profit organizations.
Examples include http://www.un.org, http://www.unicef.org
The .edu top-level domain name is meant specifically for educational institutions that reside in the United States. Examples include http://www.dartmouth.edu; http://www.theamericancollege.edu
The .gov is another top-level domain which use is only limited to governmental organizations in the United States. Examples include www.usa.gov; www.cdc.gov
The .mil top-level domain is reserved for military organizations in the United States. Examples include http://www.dla.mil, www.army.mil
