interjections

An interjection (also known as an exclamation) is a word, phrase, or sound that people use to express their sudden feelings, emotions, or reactions. For example, if you are excited, you might say "Wow!" or "Yay!". If you are surprised, you might say "Oh!".  People also use interjections to greet others.

• Hey! How are you doing?
• Yay! We won the game!
• Ouch! That hurt.
• Well, I never expected to see you here.

Interjections are often standalone words or short phrases that don't have a grammatical connection to the rest of the sentence.

We use an exclamation mark (!) when the emotion is very strong.

• Oh no! I forgot to bring my wallet.
• Oops! I didn't mean to spill that.
• Ah! That makes sense now.

We should use a question mark (?) if the interjection expresses disbelief, uncertainty, or curiosity.

•  Huh? Seriously? That's incredible!
• Well? Would you like to hear more about it?
• What? Again? That's unbelievable! 

The interjections "er" and "um" are often used in spoken language. They are known as hesitation or filler words and are used when someone is pausing, thinking, or hesitating during conversation.

• The meeting is, er, scheduled for 3 PM, and, um, everyone is expected to attend.

We typically avoid using interjections in formal writing. However, in everyday speech and informal writing, interjections are quite common.