In English they are used to combine two words in order to form a new one ("a 3-hour long journey, good-looking, ice-cream). Some words are spelled with or without a hyphen, as different schools of grammar have conflicting views on the matter (such as "no one" and "no-one", "ice-cream", "icecream" and "ice cream").
Hyphens not needed
Yes, you use hyphens for the phrase "top-of-the-line." It is a compound adjective that contains a preposition, so it is hyphenated.
Most people would spell it sixteen-year-old child. But over the last 20 years, people are ignoring the hyphens.
No. Use hyphens when creating a compound adjective, for example a two-foot width or a four-foot depth.
No. The phrase is spelled "by the way" (an aside). You would only use the hyphens if the phrase "by the way" was being used as an adjective, as is seen in the term "out-of-the-way location."
No, apostrophes and hyphens serve specific functions in writing. Apostrophes are used to indicate possession or contraction, while hyphens are used to join words or to clarify the meaning of a word or phrase. Both punctuation marks are important for clarity and proper grammar.
There is no need to hyphenate this expression.
Hyphens not needed
There are no hyphens in the word ago.
A single dash that is used to connect words to create a compound word.
The terms pre-register and pre-registration are still used with hyphens, mainly for clarity. But most dictionaries now list the words without hyphens, as preregister and preregistration.
When text is followed by two hyphens and then a space, the two hyphens are often changed to an em dash (—) in some word processing programs and websites with automatic formatting. It is used to indicate a break in thought or emphasize a statement within a sentence.
You use hyphens to make compound words that are not recognizable in common usage.
It changes the hyphens into end dashes.
If you're using the phrase as an adjective (example "This easy-to-use remote is great!") then it will definitely need the hyphens. Otherwise, the hyphens are incorrect.
— Just remember that when using hyphens, they are hyphens, not –, and – should be used for between times like this Come to Answers.com between 7 – 8 The Answer to the questions is "On-site"
It changes the hyphens into end dashes.