Although I've been out 'of the loop' for a few years I don't think the basic philosophy in this area has changed.
Software is the instruction sets that make up all applications or 'programs'.
When you start running a program it is read from the hard drive into your ram memory. Depending on the amount of ram you may have a number of programs active at any given time. Actual operation of your programs take place in ram although some data may be retrieved from or stored to the hard drive during the operation. Now for a brief description of your hard disk. Use a phonograph record as an analogy.