Memory refers to a physical device which is used to store programs or data on a permanent or temporary basis.
There are generally two types of computer memory volatile and non-volatile. Primary memory is used to refer to any form of computer memory which are fast and usually volatile (e.g. RAM - Random Access Memory) and secondary memory is used to refer to non-volatile, or robust, devices for storage. These memory devices usually store larger programs or documents and are usually permanent. Primary memory is faster to access than secondary.