Software: Method Draw
The Method Draw program is a web-based vector graphics program that offers a simple and streamlined user experience. It removes some of the more advanced features to avoid overwhelming users. It is for this reason that this program is a great tool for new users as well as the fact that it can be accessed from a web browser. More information on Method Draw can be found on their website.
Navigate to https://editor.method.ac/ to start using Method Draw.
Method Draw is entirely open-source; the source code can be found on GitHub here.