Expression

An expression is a word or group of words used in a particular situation or by particular people.

In English an expression doesn't always have a particular grammar structure but is commonly used in spoken English.

Examples :

• OK!
• Oh my god!
• See you later! 
• What’s up?
• How’s it going?
• How are things?
• How about you?
• Pretty good.
• Same as always.
• Could be better.
• Can't complain.
• No problem.
• No worries.
• My pleasure.
• Anytime.
• Anyway, ...
• I have no idea.
• Exactly.
• Absolutely.
• That’s for sure.
• I couldn’t agree more.
• You’re telling me!
• I’ll say!
• I suppose so.
• That’s great!
• Poor you.
• Sorry!
• Alright!
• What a day!
• Fancy meeting you here!