Terraforming Mars will be a huge task. Initial stages of terraforming Mars could take several decades or centuries and terraforming the entire planet into an Earth-like habitat would have to be done over several millennia. Our first steps will have to be small and steady to create an environment sustainable for human colonization. We will slowly progress into developing Mars into a planet like Earth, with hopes of creating another world capable of sustaining life in a safe and natural atmosphere. Seeing how terraforming has never been tried before, changing the Martian environment will be a long and hard experiment with a possibility of outcomes.
To transform the dry desert-like land into a lush environment, where humans, plants and animals can survive, a number of terraforming methods have been proposed.