Androids were introduced into Maplestory in the start of the Chaos Update. They can be created as a Blacksmith, albeit the recipes are a very rare find. Androids are designed to be your most loyal friend and supporter. They are similar to pets in the way that they follow you wherever you go and will obey specific commands. Androids come in a preset outfit and they can be dressed in your own style, but they can only wear NX based clothing.
However, making an Android doesn't mean you can use it. Activating an Android requires a Heart, which can also be created by Blacksmithing. The con of hearts is that they are temporary and only last for 2 weeks. However the pros outweight the cons due to the fact that unlike other recipes, once you use any heart recipe, the recipe is permanent and stays with you, even after use and that the hearts can use ANY scroll to its advantage and if that's not enough, it can even gain Potential, so a good Heart recipe is a must for a good Android.