Whether we like it or not, punctuation tells a reader the meaning and emotion of a sentence, and makes it easier to read. Learning to use it correctly will help you a lot as a writer.
All sentences end in some sort of punctuation, whether it’s a period, exclamation mark, question mark or ellipsis. If you don’t use punctuation, your reader doesn’t know when one sentence ends and the next begins. The punctuation you use changes the meaning of what you’ve written.
That’s a dog. (Period used, it’s a fact.)
That’s a dog! (Exclamation mark used, it’s a fact with excitement.)
That’s a dog? (Question mark used, it’s an inquiry.)
That’s a dog… (Ellipsis used, the thought was never finished.)
Using commas is important as well. A comma is where you’d take a pause to breathe if you were talking, and tells the reader to pause.
Without commas you’d get sentences like this that while they do have something to say they’re really hard to read because they never stop if they don’t stop it gets really confusing to read.
Wow, that was bad, wasn’t it? That’s why you need commas, or to make what you’ve written into more than one sentence.
In other punctuation… The ellipsis means that something is missing. Either you left something out, like perhaps a curse word, you took a long pause, or the thought was never finished.
A colon (:) is used before a list or example.
A semicolon (;) is used when you could have made two sentences, but made one. If used correctly you can substitute “but”, “and” or another conjunction and the sentence will still make sense. For example:
I gave him three dollars; he blew it all on candy. I gave him three dollars and he blew it all on candy. I gave him three dollars but he blew it all on candy.
Generally speaking, You never use more than one punctuation mark at the end of a sentence. In modern times the use of ?! or !? is accepted in casual writing, but not in formal writing.
In almost all cases you should only use one space after a punctuation mark. Apostrophes and quotes break that rule, but when using a period, comma, exclamation mark, question mark, ellipsis, colon or semicolon, use just one space afterward. Don’t leave out the space or use two spaces. (Some particular places may require double spacing, but only use it if the specific guidelines call for it.)