Notes is a built-in that allows users to make, share and delete notes from iPhone, iPod Touch, iPad and Mac. Notes app has been on iOS since the original iPhone and were added to Mac in OS X Mountain Lion. Notes can be synced using cloud services such as iCloud and Gmail.
Notes on iOS can only hold text. Notes on Mac allow creation of folders, insertion of images, attachments and hyperlinks, choosing different fonts, text sizes, formatting lists, choosing the alignment (left, center, justify, or right), assigning a writing direction, and indentation of text. They can also be pinned to desktop for easy access.
Notes on iOS can be shared using AirDrop, mail and messages (SMS and iMessage). Notes can also be copied to clipboard and printed using AirPrint.
Notes on iOS has changed dramaticly only in iOS 7, which added a AirDrop sharing and new look and feel. Other versions of iOS added AirPrint, copying and iMessage (not to be confused with SMS, which was there since the original iPhone) sharing. Notes app before iOS 7 also supported Noteworthy, Marker Felt, and Helvetica fonts, however Noteworthy and Marker Felt fonts were removed. Notes were added to Mac with the release of OS X Mountain Lion and haven't changed since than.