Is it a hyphen? Is it a en dash? An em dash? What do I use?!?

 A Dash is a Dash is a Dash – Or Is It?  Lions and tigers and bears–oh my! More like hyphens and dashes and–more dashes. Oh Lord! The dash, the en dash, and the em dash. The Three Musketeers of the writing world. The Holy Trinity of the literary apocalypse. The–okay, you get it. These simple lines on paper (or a computer screen) are enough to make the staunchest writer quiver if they don’t know when to use which. No, don’t run away. It’s okay. No need to panic. This is easy. Really. Check it out:

    Em Dash (—): Denotes a pause in thought, a parenthetical statement, or — more casually — an afterthought.  Modern word processors will automatically insert an em dash when you type a pair of hyphens.
    En Dash (–): Denotes a range, especially of numbers, such as $100–150. – in a web page or ALT-0150 on a keyboard.
   Hyphen (-): Used for the hyphenation of words (co-ordination; able-minded; pre- and post- touring.) Just use the keyboard key for this one.   Thank you to www.kajhaffenden.com for the above definition and shortcuts.

I use the em dash a lot! This from http://www.thepunctuationguide.com/em-dash.html

Em dash
The em dash is perhaps the most versatile punctuation mark. Depending on the context, the em dash can take the place of commas, parentheses, or colons—in each case to slightly different effect.

Notwithstanding its versatility, the em dash is best limited to two appearances per sentence. Otherwise, confusion rather than clarity is likely to result.

Em dashes in place of commas
A pair of em dashes can be used in place of commas to enhance readability. Note, however, that dashes are always more emphatic than commas.

And yet, when the car was finally delivered—nearly three months after it was ordered—she decided she no longer wanted it, leaving the dealer with an oddly equipped car that would be difficult to sell.

Em dashes in place of parentheses
A pair of em dashes can replace a pair of parentheses. Dashes are considered less formal than parentheses; they are also more intrusive. If you want to draw attention to the parenthetical content, use dashes. If you want to include the parenthetical content more subtly, use parentheses.

Note that when dashes are used in place of parentheses, surrounding punctuation should be omitted. Compare the following examples.

Upon discovering the errors (all 124 of them), the publisher immediately recalled the books.

Upon discovering the errors—all 124 of them—the publisher immediately recalled the books.

When used in place of parentheses at the end of a sentence, only a single dash is used.
After three weeks on set, the cast was fed up with his direction (or, rather, lack of direction).

After three weeks on set, the cast was fed up with his direction—or, rather, lack of direction.

The em dash in place of a colon
The em dash can be used in place of a colon when you want to emphasize the conclusion of your sentence. The dash is less formal than the colon.

After months of deliberation, the jurors reached a unanimous verdict—guilty.

The white sand, the warm water, the sparkling sun—this is what brought them to Hawaii.

Multiple em dashes
Two em dashes can be used to indicate missing portions of a word, whether unknown or intentionally omitted.

Mr. J—— testified that the defendant yelled, “Die, a——,” before pulling the trigger.

From the faded and water-damaged note, we made out only this: “Was ne——y going to m—— K——, but now ——t.”

When an entire word is missing, either two or three em dashes can be used. Whichever length you choose, use it consistently throughout your document. Surrounding punctuation should be placed as usual.

The juvenile defendant, ———, was arraigned yesterday.

Spaces with the em dash
The em dash is typically used without spaces on either side, and that is the style used in this guide. Most newspapers, however, set the em dash off with a single space on each side.

Most newspapers — and all that follow AP style — insert a space before and after the em dash.

Producing the em dash
Modern word processors will automatically insert an em dash when you type a pair of hyphens.