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.