The words following a colon do not usually start with a capital letter, unless the introduction is short and the words after the colon are the main idea and a complete sentence.
A Capital Letter to Start a SentenceStart every new sentence with a capital letter. This seems like a fairly simple ruling, but there are some quirks.
Capital Letters after Colons, Dashes, or SemicolonsWhen a sentence is divided by a dash, a semicolon, or a colon, you will often have two "sentences" either side of it. In fact, these are not two sentences but two independent clauses. Only the first one (i.e., the one that starts the sentence) gets a capital letter. For example:
- In this world there are only two tragedies: one is not getting what one wants, and the other is getting it. (Oscar Wilde) (Note: No capital letter on one.)
- Our motto: Live every day to the fullest – in moderation. (Lindsay Lohan)
Of course, if the first word should have a capital letter in its own right (e.g., it's a proper noun (e.g., London, George Harrison, Wal-Mart) or an abbreviation (e.g., CNN, BBC, Nato)), then obviously it keeps its capital letter.
Capital Letters within Quotation MarksIf your sentence contains a quotation which is a standalone sentence, start the quotation with a capital letter. For example:
- At 4 o'clock, he stood up and said: "You can all leave if you wish." (In this example, the quote is a standalone sentence. Therefore, it gets a capital letter.)
- He was considered "the sexiest man ever to come out of Barnsley." (Here, the quote is a not a standalone sentence.)
Once you have expressed a complete idea, you must put a full stop and end the sentence. Do not insert a comma and continue writing. This is a very common mistake. For example:
- John sprang to his feet and ran to the shop, he needed to buy more beer before the second half started.
- The Loch Ness Monster was spotted 8 times in the '60s, I camped there for a year and did not see a thing.
Read more about run-on errors.
YOU CAN EXTEND A SENTENCE...JUST NOT WITH A COMMA
Occasionally, it may be appropriate to use a colon, a dash, or a semicolon to extend a sentence. For example:
- John sprang to his feet and ran to the shop; he needed to buy more beer before the second half started.
The word however (usually written However,) nearly always starts a new sentence. It is a common mistake to merge sentences using a comma and however. For example:
- I am leaving on Tuesday, however, I will be back on Wednesday to collect my wages.
- I am leaving on Tuesday. However, I will be back on Wednesday to collect my wages.
- Do not feed the fish in this tank, however, you may feed the animals in the petting zoo.
- The centre forward is very fast. However, he can only kick the ball with his left foot.
Read more about using a semicolon before however.
OF COURSE, HOWEVER DOES NOT ALWAYS START A SENTENCE
Be aware that the word however does not always start a new sentence. For example:
- John has confirmed that he can attend the meeting on Saturday. Simon, however, is out of the country until Monday. (In this example, the word however is a parenthesis.)