Where can you find a calendar icon?

Depending what device one is using and what one wants the calendar icon to do. One could use the calendar that is built into the Apple products like mac, itouch, ipad or iphone. Which all have built in calendars with alarms and the capability to stream and backup information to the cloud network. Also, Windows devices have their own built in calendars as well on the bottom toolbar with the time and date. Also, they have desktop calendars for computers under settings depending what version of Windows one is using. There are also many different calendar software programs that one could download as well.