Mechanics and Punctuation

Basic Punctuation


Mechanics are the small parts of your writing that stick everything together to ensure that everything makes sense and that emphasis is placed where you want it to be. Basic punctuation mechanics include commas (,), colons (:) and semicolons (;), apostrophes (‘) and hyphens (-).

When used properly, these mechanics give your sentences the meaning they should have. However, when used incorrectly, they can transform the meaning of the most basic sentence and leave your readers completely baffled as to what you are trying to tell them.

Table 1 contains some basic punctuation mechanics rules that you should apply when writing. This table is not extensive, but provides the most important ‘do’s and don’ts’.

Table 1: Basic punctuation mechanics rules

Punctuation Component Do Do Not
Comma (,)
  • Use to split up sentences
  • Use where there is a pause
  • Overuse (can make your writing more confusing)
Colon (:)
  • Use before listing items
  • Confuse colons and semicolons
Semicolon (;)
  • Use to join sentences with directly related information
Apostrophe (‘)
  • Use when something belongs (Mike’s test tube)
  • Use when contracting (we’ve, she’d, I’m)
  • Confuse with plurals (test tubes, not test tube’s)
Hyphen (-)
  • Use to link compound words (25-mile race)
  • Use after words ending in y
  • Use if the same meaning is achieved without one


You probably already use commas very frequently, but it can still be hard to always use them appropriately. If you fail to use a comma when there should be a natural pause in a sentence, like here, your readers will be confused. However, if you overuse commas, your readers will be equally baffled as to what you are trying to tell them.

Consider the two versions of a short sentence, below, that is interpreted completely differently due to the presence of a single (necessary) comma:

1: I am very hungry so we should cook Mom.
2: I am very hungry so we should cook, Mom.

And now consider the two versions of a short sentence, below, that is made more confusing by the overuse of commas:

1: Thankfully, we, the people of Scarborough, a little seaside town, are deeply, and passionately involved, in nature conservation.
2: Thankfully we, the people of Scarborough, a little seaside town, are deeply and passionately involved in nature conservation.

Colons and Semicolons

Colons should be primarily used before you provide lists of items or quote somebody, whereas semicolons are used to link closely related sentences; they can be used when the relationship between these sentences is obvious.

For example, you should use a colon when you list the five basic punctuation mechanics explained here. These are: commas, colons, semicolons, apostrophes, and hyphens. You should also use a colon with a quotation, like this: “The importance of punctuation should never be underestimated,” said Professor in Chemistry, Dr. Reilly.

You should use a semicolon only when the link between to sentences is pretty obvious. For example: Rabbits are always more vigilant when they know predators are watching them; they don’t want to risk being sneaked up on.


Apostrophes are most often used to signal ownership or to shorten compound words that have been contracted. For example, if the chemistry textbook belonged to Hoshi, you should refer to it as Hoshi’s textbook, and if you are nice to her, perhaps she’ll lend it to you. Contracted compound words like the ‘she’ll’ in that last sentence used to be frowned upon in scholarly writing as people instead preferred writing the two words in full (‘she will’). This way of thinking has generally changed now, so it’s fine to contract words, just as you’d do normally when chatting.

The most common mistake with apostrophes is to use them when you should instead simply pluralize a word. For example, make sure you don’t use an apostrophe when speaking about your recent exams (they were exams, not exam’s).


Learning how to use hyphens correctly in your writing tends to be more difficult than learning how to use the other basic punctuation mechanics outlined here. You most commonly need to use hyphens when you use adjectives to modify the meaning of words that they come immediately before.

For example, the second sentence below contains a modifying adjective:

1) The hot Bunsen burner melted a nearby eraser.
2) The white hot Bunsen burner melted a nearby eraser.

Without a hyphen (as above), you would think the Bunsen burner was white in colour. The author, however, likely means the Bunsen burner was very, very hot, so you need to use a hyphen to make a compound word, like this:

3) The white-hot Bunsen burner melted a nearby eraser.

There are occasions when you need to use more than one hyphen (when you link three or more words, like ‘We dug a seven-foot-deep hole in the garden’). In all cases, when deciding whether you need to use hyphens, assess whether the meaning of your sentences would be the same without your hyphens. If it would, then you don’t need them. This is usually true when you use words ending in y to modify other words. For example, you don’t need a hyphen between ‘happily’ and ‘married’ in the following sentence, because the meaning would be the same:

We are a happily married couple = We are a happily-married couple.

Video Resource

For a recap and for some extra information on using hyphens appropriately in your science writing, please watch Grammar Squirrel’s video on the UBC Science Writing YouTube channel.

We then suggest you complete the quick quiz (below) to see whether you have mastered some of the important skills relating to hyphenation.

Basic Punctuation

  • 7. Read the following sentence and decide which comma (of those numbered throughout) should not be included: Incredibly,1 space travel is now a realistic expectation for people under 40 and for members of older generations,2 who are willing to spend the money,3 to jump aboard commercial ‘flights’,4 to outer space in the next 10 years.
  • 8. Read the following sentence and decide at which points (of those numbered throughout) a comma should be included: Students are often surprised1 when2 without warning3 their instructors tell them they are about to sit a pop quiz4 that probes their understanding of recent topics discussed in class.