Although the Arduino is a compact development platform, with examples like the Arduino Nano and Arduino Pro Mini being particularly pocketable, sometimes you find yourself eager to try something out but without access to hardware - either the Arduino itself or the components needed for your particular circuit. Traditionally, the solution to this problem is to walk through your design using good old fashioned pen and paper, but there are alternatives.
One such alternative is Autodesk Circuits, a web-based platform which allows you to design projects in a visual environment and run them on a simulated Arduino Uno. Maker Christian Bodington is currently publishing an impressively detailed guide to using Autodesk Circuits, starting with the basics and running through a constantly-updated string of increasingly-complex projects which really showcase the impressive capabilities of the platform.
The strengths of Autodesk Circuits are its ability to step through your program line-by-line, providing an invaluable aid to debugging, and its visual breadboarding system which works in a similar manner to the popular Fritzing circuit design tool. Experts, though, are likely to find it restrictive, especially when it comes to hacking around with unusual hardware in unusual ways.
Before you buy an Arduino Uno, you need to know that you can simulate a lot of ideas just using Autodesk Circuits. The purpose of this Instructable is to make a guide that allows the user to learn to simulate programming for Arduino Uno through the web application Autodesk Circuits, building a lot of examples that will guide them in learning to program I/O ports, serial communication between devices, electric motors and servo motors, 7-segment displays among others.