Need to do list

When you are in work, many things come in your mind, which you want to do later. And then after some time you forgot everything. In office I had made a note pad file and keep it on desktop. I started writing on it whatever I wanted to do. Some times this list became very long but whenever I get a minute I read this list and selected one what I can do on that moment and did it. After finishing the work I deleted that note from the list. This way I made this list shorter but could never made it empty. There are many ways to store this list. But you should select the way which you can follow always.