For example, d/example is the domain name example.bit , and id/example is an identity.

The Namecoin software is used to register names and store associated values ter the blockchain, a collective database distributed by a P2P network te a secure way. The software can then be used to query the database and retrieve gegevens.

Do I need to back up my wallet?

If you’re using Namecoin to register or otherwise own names, or to transfer namecoins, then you do need to periodically back up your wallet.