What is an interjection? Alice and I will teach you! :)
An interjection is a word that shows emotion.
It's not grammatically related to the rest of the sentence.
Interjections are usually one to two words that come at the beginning of a sentence.
They can show happiness (yippee), sadness (aww), anger (grr), surprise (holy cow), or any other emotion.
Interjections aren't grammatically related to the rest of the sentence.
What does that mean, anyway? Well, it means that unlike all of the other parts of speech, the interjection does not interact with any other words in the sentence. It doesn't modify anything, and it doesn't get modified by anything. It doesn't play the role of subject or verb.
It pretty much just sits in its lonely little interjection corner and expresses emotion. Geez, that sounds pretty sad... poor little guys.
Diagramming sentences is a visual way to show how the words in a sentence are related to each other. Look at the diagram below.
It's easy to see that interjections aren't grammatically related to the rest of the sentence because they float on lines hovering above the rest of the sentence! They're not joined to any other part of the sentence.
That's a pretty good way of showing that they aren't related to any of the other words, isn't it?
You can diagram more interjections here if you'd like.
How do you punctuate interjections?
Interjections are punctuated with an exclamation mark or a comma. Use an exclamation mark if the emotion is very strong.
Wow! I won the lottery!
Use a comma if the emotion is not as strong.
Wow, I have a peanut butter sandwich for lunch.
What is an interjection? Beware!
Don't get fooled into thinking that all introductory words followed by an exclamation point or a comma are interjections. They're not!
Hmm... What is an interjection? Do you remember?
It is a word that shows emotion. So, if the word in question does not show emotion, it is probably not an interjection. Let's take a look.
Maria! Come and see the lion!
Names like this one are not interjections. They're nouns because they name people. When you say someone's name when you talk to them, it's called direct address. Names also don't fit our definition of an interjection because they don't show emotion. The tone of voice that you say them in may show emotion, but the name itself does not.
Stop! The lion will eat you!
Stop isn't an interjection either. It's a verb because it shows action. (It's also a complete sentence! This kind of sentence is called a command or an imperative sentence.)
Although the sentence as a whole does convey a sense of urgency (Who wants to get eaten by a lion?), the word stop isn't showing emotion.