An interjection expresses a sudden unexpected reaction to a particular situation.

Interjections are words that mean joy, surprise, sorrow, excitement, pain, or anger.

Almost always, an exclamation point (!) follows an interjection.

Examples:

• Wow! I'm seeing a friend whom I haven't seen for 25 years.

• Oh! What a painful experience.

The words wow and oh are interjections. Wow expresses pleasure and oh expresses pain.