The "new kid on the block" is treated pine. It's one of the most popular decking materials because it is one of the least expensive and can create a nice appearance.
Although you can paint or stain your deck as you like, pine takes stains and paints beautifully. Treated pine, on the other hand, is not all created equal. The “H” (Hazard) rating may tell you whether it's safe for outside use and whether the posts can come into contact with the ground. A competent decking supplier could be able to advise you on the appropriate “H” rating for your decking, joists, posts, and other components.