Illustrator how to remove blue line previews?

[Lea227957047qpt]

Hi, I literally just started using Adobe Illustrator and I cannot figure out what is wrong with my paintbrush tool. Every time I make a stroke, a blue preview line thing appears, and only when I lift my pen does the actual line get applied. I know there's a way to shut this off, because I've seen countless videos of people drawing normally, without the blue preview line. How do I turn off the blue thing?

[Ton Frederiks · Accepted solution]

Art and Pattern brushes don't have a live preview when drawing. Calligraphic and Bristle brushes do.