Google Keep is probably the best note app available for Android at the moment. This is a great way to keep track of the things you need to remember, especially since all of your notes appear on all of your devices because everything is related to your Google Account. Store just reached 500 million downloads on the Play Store, which is not a small feat. Although it is pre-installed on some devices, we're giving good chances that many of the 500 million downloaded files are from people who actually wanted to install the app.
I have not tried Google Keep in any way, you definitely have to. You can download it via the application widget or the source link as below.