Tip: Add Line Numbers to Your Code-Behind Classes
Posted by Ion Toma on April 17, 2006
Adding Line numbers to your code can be very helpful when discussing the code with someone else.

How to add line numbers to the code: from Tools menu, select Options, and then the Text Editor / C# or Basic options. Select then the "Line numbers" checkbox om the right-side.

Also, it works well with word wrap, you can see when a line starts and ends.
Another way to bring lines to your code is using Macro Explorer Tool window; there is a build in macro built-in that allows to turn on/off the line numbers.
Note: the line numbers are in the code, they are just displayed in a column to the left.