I all wanted to know, but thatnks to Google that all you need to do, if you are looking for that perplexing answer. So accoding to http://www.sciencemadesimple.com/leaves.html
Winter days are short and dry. Many plants stop making food in the fall. The chlorophyll goes away. Then we can see orange and yellow colors. These colors were in the leaves all summer, but the green covered them up.
Some leaves turn red. This color is made in the fall, from food trapped in the leaves. Brown colors are also made in the fall. They come from wastes left in the leaves. Now doesn't that make perfect sense?