Emphasis, aka italics, with asterisks or underscores.

Strong emphasis, aka bold, with asterisks or underscores.

Combined emphasis with asterisks and underscores.

Strikethrough uses two tildes. Scratch this.

• Unordered list can use asterisks
• Unordered list can use asterisks
• Unordered list can use asterisks

1. First ordered list item
2. Another item

I'm an inline-style link

I'm a relative reference to a repository file

You can use numbers for reference-style link definitions

Inline-style:

Reference-style:

Inline code has back-ticks around it.

var s = "JavaScript syntax highlighting";
alert(s);

No language indicated, so no syntax highlighting. 
But let's throw in a <b>tag</b>.

Colons can be used to align columns.

There must be at least 3 dashes separating each header cell. The outer pipes (|) are optional, and you don't need to make the raw Markdown line up prettily. You can also use inline Markdown.

Blockquotes are very handy in email to emulate reply text. This line is part of the same quote.

Quote break.

This is a v

Here's a line for us to start with.

Hyphens

Asterisks

Underscores

Here's a line for us to start with.

This line is separated from the one above by two newlines, so it will be a separate paragraph.

This line is also a separate paragraph, but
This line is only separated by a single newline, so use two spaces.