Imaging hard drives is the process of taking a hard drive and copying it bit by bit to create an exact replica, in a way an “image” just like a photograph of a person is a snapshot of them at any moment in time. The cloning part is the process of taking that “image” of a hard drive and placing copies of it on one or more other hard drives.
In a cloning project I worked on, my favorite freeware product from my googling journeys was Clonezilla. Clonezilla is free! Clonezilla is a good tool for taking a snapshot of a system and reverting back to it later as a backup or to get things the way you once liked them.
When you have a new computer and begin installing software that you enjoy using, that would be a great time to image the hard drive in case something happens later. This can save time instead of having to reinstall your operating system if there is a virus or corruption in data. Creating a copy of a hard drive can also save you from ruining the state of a computer due to tinkering, installing software, etc. If you do PC repair for customers or as a hobbyist, you can also use this software before beginning work on some computers in case you would need a point of reference for any reason. Clonezilla, clones a 40 gigabyte hard drive in about 15 minutes.
Clonezilla has two forms, Clonezilla live and Clonezilla ServerEdition (SE). Clonezilla live is used for cloning single machines while Clonezilla SE is for multiple machine deployments.