1. Vertical lines

I already know how to do horizontal lines. It seems like the keyboard is supposed to have a symbol for vertical lines which I don't see. Any suggestions?

2. Usually it's the key right above the Enter key. Hold down shift + that key. You should get "|" as a result.

3. Nice. The key shows it as a broken line (darn library), but it works.

4. Since this is a LaTeX forum, I thought I'd share this. I read recently that there are three ways to type a vertical bar in LaTeX: | (synonym: \vert), \lvert and \rvert, and \mid. The first produces an ordinary math symbol like letters and digits (class \mathord); the second makes opening and closing delimiters (\mathopen and \mathclose), and the third produces a binary relation (\mathrel). Each class is inserts its own spaces. For example, there is a thin space \, between an ordinary symbol and an operator, but no space between an opening delimiter and an operator: compare $\displaystyle |\sin x|$ and $\displaystyle \lvert\sin x\rvert$. The relation \mid is good for set notation $\displaystyle \{x\in\mathbb{N}\mid x<5\}$ and to denote divisibility.

5. Here are more ways to do this.

$$\left|\sin(x)\right|$$ gives $\displaystyle \left| \sin(x)\right|$

$$\left\|\sin(x)\right\|$$ gives $\displaystyle \left\| \sin(x)\right\|$