Mac OSX operating system features an application called Time Machine. You can use this built-in application for all your backup purposes. As it's suggested, you should use Time Machine for simple backup purposes, but it's best to use another application along with Time Machine. You can try Carbon Copy Cloner because it will provide additional features beside Time Machine and it will offer advantages for manipulating your disk images, backups, synchronization tasks.
Please note that CCC application is free although there is a purchase button. That is for something else, the application will work just fine.