You should not capitalize a sentence fragment following a colon.
You use one space after a colon or semi-colon.
A colon causes a pause in a sentence. I hope that was simple enough for ya.... sarcasum intended.
Such an interruption requires a comma, you may wish to use a Colon or a Semi Colon depending on the construction of the sentence
As with a comma, a semi-colon (;) separates items (i.e., a list or set of ideas, etc.) within a given sentence. Therefore, it is one sentence.
If a colon is required in the sentence in which the abbreviation occurs, there is no rule against a period preceding the colon.
Not unless a proper noun follows the semi-colon. The parts before and after the semi-colon are part of the same sentence. You do not capitalize in the middle of a sentence unless it is a proper noun.
A colon instead of a semicolon may be used between independent clauses when the second sentence explains, illustrates, paraphrases, or expands on the first sentence. Example: He got what he worked for: he really earned that promotion.
The colon should follow an independent clause, which is a complete sentence that can stand alone. This helps to set up the list that follows the colon.
Use a semi-colon instead
She had one goal for the summer: to improve her tennis skills.
No, colons should not be underlined. When using a colon, it should be formatted as regular text within a sentence.