Interjections

"Like, dude! Whoa!"

This sentence is linguistically incomprehensible (i.e. we can’t understand what is being discussed), but we understand the tone it implies: the speaker is clearly worked up about something. We don’t know whether the speaker is happy or angry, but if we heard this sentence while walking down the street, we’d all turn our heads and look to see what exciting thing is happening.

Incomprehensible sounds such as "Whoa!" are used in the above sentence – or words used out of context – have a grammatical term for them: interjections. Interjections are usually found at the beginning of the sentence, as we use the interjection either to get someone’s attention (“Hey! Watch out!”) or to give ourselves time to think about the real words (Oh, yum! This burnt, over-salted cake is utterly scrumptious!)


+ What Are Interjections?
Interjections are words like 'wow' and 'yay'. They’re sounds we make – to convey extreme emotion or to create emphasis – when we’re talking, sometimes when we can’t think of a good way to express ourselves. The problem with interjections is that, because they’re technically meaningless, they require a great deal of context to be understood. For instance, 'hey' can mean 'hello', or 'that’s great', or 'stop doing that'.

"Hey! How are you?"
"Hey! That’s an awesome hat!"
"Hey! Cut that out!"

Interjections are frequently followed by an exclamation mark.

Interjections (and exclamation marks) are generally frowned upon in formal writing.

Interjections are not grammatically connected to any part of the sentence (i.e. they don’t modify a verb or a noun, etc.) They can be removed without creating confusion.


+ Uses of Interjections:
Interjections are used to communicate an extreme emotion which is difficult to verbalize, or to get someone’s attention. They’re usually found at the beginning of the sentence. Because they are not grammatically connected to the rest of the sentence, they are often followed by an exclamation mark (or sometimes a comma).

"Gee, I love old movies!"
"Whoa! That’s a lot of homework!"
"Oh, drat! It seems we forgot to pay the electrical bill."

Sometimes, we use a word which usually has meaning, but in the context of the sentence it’s merely for emphasis.

"What was I talking about? Oh, yes, now I remember…."

Here, yes is not actually being use as an affirmation (to answer “yes” to a question). It’s just an interjection.

"We thought Max wasn’t coming to the family reunion and then, good lord, there he was!"

"Good lord" isn’t being used to address any god; it’s just adding emphasis to the fact that Max had unexpectedly arrived at the family reunion.


+ Interjections List:
Here are some examples of interjections:

aha, ahem, ahh, ahoy, alas, arrggh, aw
bam, bingo, blah, boo, bravo, brrr
dang, drat, darn, duh
eek, eh, encore, eureka
fiddlesticks
gadzooks, gee, gee whiz, golly, goodbye, goodness, good grief, gosh
ha-ha, hallelujah, hello, hey, hmm, holy buckets, holy cow, holy smokes, hot dog, huh, humph, hurray
oh, oh dear, oh my, oh well, ooops, ouch, ow
phew, phooey, pooh
rats
shh, shoo, shucks
thanks, there, tut-tut
uh-huh, uh-oh, ugh
wahoo, well, whoa, whoops, wow
yeah, yes, yikes, yippee, yo, yuck

http://www.grammarly.com/handbook/grammar/interjections/