Illustrator

Adobe Illustrator (Ai) is a professional vector-based design and drawing program.  In Illustrator you can design a single element like a symbol or logo, or a full composition like a poster!   Unlike Photoshop, there are no pixels in vector graphics (see video on "What are Vector Graphics?").  Vector drawings begin with the smallest part called an "anchor" and is sometimes referred to as object-drawing or outline art.  

Adobe Illustrator Beginner Tutorials

https://helpx.adobe.com/illustrator/tutorials.html

BASIC SHAPES:

https://helpx.adobe.com/illustrator/how-to/shapes-basics.html

Ai Pen Tool Resources

Adobe Illustrator Pen Tool Tips and MORE:

https://digitalsynopsis.com/design/adobe-illustrator-pen-tool-tips/

Adobe’s HelpX How to Use the Pen Tool:

https://helpx.adobe.com/illustrator/how-to/use-pen-tool.html

Comprehensive Guide by EnvatoTuts+:

https://design.tutsplus.com/tutorials/illustrators-pen-tool-the-comprehensive-guide--vector-141

YouTube Videos on Pen Tool:

Drawing Simple Curves with the Pen Tool

Perfect Curves with the Pen Tool