Terraforming other planets

One day in the far future humans will learn to terraform other planets using astonishing engineering techniques and living things to turn a dead world into a living planet. But getting to planets outside our solar system will be hard and may take us thousands of years. However there are two planets we could attempt to terraform in our own solar system. These are Mars and Venus, and each presents great challenges for future terraformers. For Mars it will be warming a frozen world and then finding the right life forms to help the process as many of the most cold tolerant species may become extinct as our climate warms due to global warming and greenhouse gasses. For Venus it will be finding ways to cool a superheated planet, and then finding heat tolerant species which can survive high temperatures and the lack of a moon.