I'll talk a little first.
What is pen sensitivty? Well basically,
It allows you to vary the width of your pen strokes with how much pressure you apply to it, and almost essential to digital art.
You can notice tapered ends to the strokes with pen pressure but the same width in the strokes without.
Please don't forget to install/update your driver! It is NOT optional! Please install it. You should be able to find your drivers online easily by doing a simple google search of your tablet model + "driver". (ALSO NOTE: Yes, you NEED to have a pen tablet in order to use pen pressure. It is 100% necessary!!! The brand does not matter, but the most popular is Wacom. You can find super cheap small second hand tablets on ebay if you want to start out small, and if you draw a lot, it is definitely worth the investment.)
Common tablet brands and the link to their list of drivers:
- Wacom drivers: