Sometimes we need to create marks to remember text positions. For creating a spot just switch to NORMAL mode, then place the cursor on the desired line then press:

<Control-b>

It will shade the line, in order to unshade just press again the same Keycomamnd.

<Control-n>

It will make the cursor jump to the previous shaded line.

<Control-m>

It will make the cursor jump to the next shaded line.

Switch to NORMAL mode, then press:

<Control-q>

It will appear an inputbox widget in which you can insert the desired position to place the cursor on. Try inserting the following values

3
4 
4.2
2.3

In a file with more than 5 lines.

Some plugins may use vy spots plugin functionality to improve utility. It happens with html_checker plugin, html_checker plugin creates spots over lines with errors, then it is possible to jump back/next to the errors by using spots's keycommands.