How do you access context-sensitive help in Cisco IOS, and what can it tell you?

Type ? at any prompt — it lists the commands available, commands starting with given characters, and the arguments/keywords a command accepts.

Enter a question mark (?) at any prompt to access context-sensitive help.

It helps answer:

• Which commands are available in each command mode?
• Which commands start with specific characters? (e.g., te? shows telnet, terminal)
• Which arguments and keywords are available for a particular command?

Example:

Router#ping ?
  WORD  Ping destination address or hostname
  ip    IP echo
  ipv6  IPv6 echo

Go deeper:

• Jeremy's IT Lab — Intro to the CLI (CCNA Day 4) — shows ? context-help, tab completion and command abbreviation in action.