This article explains what ISO files are and provides examples of the different ways you can use them.
What is an ISO file?
An ISO file, often referred to as an ISO image, is a single file that is a perfect representation of an entire CD, DVD, or BD. The entire contents of a disc can be accurately duplicated in a single ISO file.
Think of an ISO file as a box containing all the parts of something that needs to be built, like a child's toy that you might buy and need to assemble. The box that the toy pieces come in isn't really a toy, but the contents inside, once taken out and put together, become what you actually want to use.
An ISO file works in much the same way. The file itself is worthless unless it can be opened, assembled and used.