Fortunately, English only has around a dozen punctuation marks, and they each do definite things.
Like grammar, they shouldn't scare you - they only make you more powerful when you can use them comfortably.
A full stop finishes a sentence.
| Good writing is useful. |
Commas separate the parts of a sentence. Well-known examples are items in a list (1), a modifier before the sentence (2), or extra information inside the sentence (3 - notice the commas before and after the extra piece).
| (1) | Good writing is useful in study, work, finance and daily life. |
| (2) | Specifically, good writing is useful in communicating with other people. |
| (3) | Good writing, which is easier than most people think, is useful in daily life. |
An apostrophe shows one thing has another thing.
That is, it usually shows ownership (1) or attribute (2) (but also see "Mistakes").
| (1) | Good writing shows the writer's point clearly. |
| (2) | Good writing's main feature is ease of understanding. |
A semi-colon can be used instead of a full stop when two sentences need to go together very closely (2).
| (1) | Good writing is useful. It ensures the writer's point is taken seriously. |
| (2) | Good writing is useful; it ensures the writer's point is taken seriously. |
Don't overuse semi-colons - only when they clearly work better. They become annoying very quickly.
A colon helps you explain something.
| Good writing is useful in three areas: study, work and daily life. |
A hyphen joins the parts of a complex word.
| Good writing is useful in both low-stakes and high-stakes work. |
Dashes and brackets add extra information to a sentence if it's less important, or more separate from your main point (2-3).
| (1) | Good writing is useful for everyone in study and work. |
| (2) | Good writing is useful – for everyone – in study and work. |
| (3) | Good writing is useful (for everyone) in study and work. |
COMMON MISTAKE
Question marks and exclamation marks can also finish sentences, but are very unusual in academic writing.
Questions are only used in some rare assignment types (e.g. PhD theses). Except in those cases, they're unclear and should be written as a sentence instead (1).
Exclamation marks are unacademic - all drama and no substance (2).
| (1) | How is good writing useful? |
| It is important to consider how good writing can be useful. | |
| (2) | Good writing is so useful! |
COMMON MISTAKE
Apart from ownership (see above), apostrophes can also run words together.
This isn't usually done in academic writing - write the words in full.
| Good writing's useful, and work can't be done easily without it. |
| Good writing is useful, and work cannot be done easily without it. |
AND BY THE WAY
Referencing systems each have their own way of using punctuation. This is an annoying (but necessary) part of the process, so know which system your course uses, and get a feel for how it uses brackets, commas, colons, and so on.