Top-level domains (TLDs) are the highest ranking domains in the Internet. TLDs are labeled by the extension of their domain name, such as .com, .org or .net.
Application domains and alternative definitions
An application domain applies to a specific software application and separates it clearly from other applications. A domain-specific language (DSL) is a programming language designed only for one particular domain. For example, SQL (Structured Query Language) is a domain-specific language for database management. It applies only to certain databases.
A domain in general computer terminology is also the range of values that belong to a specific attribute: for example, the range that applies to certain data types. Within a Google Sheet, the list of possible values that the user has designated for a specific column are that column’s domain.