(Goodness I had to work hard to fit them all in there.)
Here is a really rough guide - if you want/need something better, try The Elements of Style by Strunk and White or Brilliant Writing Tips for Students by Julia Copus.
Punctuation is really all about common sense and breathing. Common sense comes into play because you're trying to make what you write comprehensible and the longer and more convoluted your sentences, the harder they are to understand. Breathing is about how we speak because punctuation should follow our speech patterns.
When I'm working as an RLF Fellow I find many students whack in colons and semi-colons because they think it makes them look more intelligent if they have lots of long, long sentences that go on and on to the point of incomprehension. Trouble is, it doesn't make them look intelligent, just waffly and confused. I reckon you can write a whole book without using colons and semi-colons - and have proved that more than once - so most of the time you don't need to use them. But if you must...
Colons (:) often have a list following them, as in the following
...using the following punctuation marks: full stops, commas, colons...
Semi-colons (;) indicate a sentence fragment that can't stand on its own two feet and needs to hang around with a bigger, badder sentence to make sense. So,
Not necessarily because educational standards have slipped, but rather that they've changed.
doesn't make sense standing on its own, it needs the previous part of the sentence to prop it up.
...the shakier your grasp on the finer points of using the following punctuation marks: full stops, commas, colons and semi-colons; not necessarily because educational standards...
Commas (,) are used when you naturally take a little breath, for example between items on a list, and full stops are when you've come to the end of that thought. Say the following out loud, and you'll find yourself going up at the end of each item of shopping (=comma) and going down at the end (=full stop).
I went shopping and I bought an apple, a banana, an orange and a pencil.
I have a habit of using what is technically called the Oxford comma (also known as a Harvard comma - I only hang out at the poshest of universities you know). If you look at the opening paragraph again I've put a comma in-between 'education' and 'but'
It depends on your education, but the chances are...
Not wrong, but it would read more easily without the comma, especially as there are more commas coming up in the rest of the paragraph.
It depends on your education but the chances are...
Sometimes you need the extra comma for the sentence to read clearly -
I dedicate this book to my children, Minnie Mouse and Donald Duck.
Are my children called Minnie Mouse and Donald Duck? An Oxford comma would make it clear that my children aren't called Minnie and Donald and I'm a Disney fan.
I dedicate this book to my children, Minnie Mouse, and Donald Duck.
Full stops (.) indicate the end of a sentence. I recommend my RLF students put in lots of full stops as two shorter sentences usually aid comprehension and make their work appear more confident and authoritative compared to one long sentence. It is not always desirable. It can make work appear abrupt. Or even, it is not always desirable as it can make work appear abrupt, but I'm sure you get the point. The opening paragraph to this post would undoubtedly read better if it wasn't one long sentence.
It depends on your education. The chances are the younger you are, the shakier your grasp on the finer points of using punctuation marks such as full stops, commas, colons and semi-colons. This is not necessarily because educational standards have slipped, but rather that they've changed emphasis.
Two extra full stops added, one Oxford comma, one colon, one semi-colon deleted, and I think it reads more easily. I am, of course, expecting to be inundated with comments saying I've got it wrong but until then,
Happy Easter everyone!