Learn in the textbookDomain Names, DNS, and How the Web Works
DefinitionA domain name (ドメイン名) is a text name, easy for people to read and remember, that points to a destination in place of an IP address, which is just a string of digits.
ExplanationWritten with dots as in example.ne.jp, it has a layered structure in which each part further right is a broader division. The rightmost division is the top-level domain (トップレベルドメイン, TLD). Domain names appear in email addresses as well as web addresses: whatever follows the @ is the domain name.
AnalogyIt is like picking a friend's name in your contacts app to place a call, instead of memorizing their number.
Memory hookDomain means territory: inside the jp territory is ne, and inside ne is example, so the territory narrows as you read from the right.