Artificial life also called Alife is simply the simulation of any aspect of life, as through computers, robotics, or biochemistry. (taken from the Free dictionary)This site focus's on the software aspect of it.
Artificial life can be anything from scientific games to simple virtual pets that you can play with. Some of the more famous examples of artificial life is Avida (1993) and the creatures series (creatures 1,2,3 and docking station). Some have artificial intelligence as well others are almost just a glorified GIF. But many use them to study real life and evolution. They are a important tool in many cases to determine results of different things effects on different environments.
This website is divided into several sections based on the kind of Alife there is. Artifical life is experiments with Alife. Virtual pets are more loosely defined and can be as simples as the Catz and Dogz games. Virtual worlds are more like games you play and you are one of the game pieces such as MMO's. The last category, Tools/coding and tutorials, is for those who wish to learn to code and create these games with tools or source code to them.