Configuration Submodes and Contexts
Configuration mode itself contains a multitude of subcommand modes. Context-setting commands move you from one configuration subcommand mode, or context, to another. These context-setting commands tell the switch the topic about which you will enter the next few configuration commands. More importantly, the context tells the switch the topic you care about right now, so when you use the ? to get help, the switch gives you help about that topic only.
Context-setting is not a Cisco term—it’s just a term used here to help make sense of configuration mode.
The interface command is one ...