Not just hard drives, but SSDs as well. The hard drive will store all your data/files/videos/photos. Large size can save a lot. Once the applications are installed, you will be taken to the hard drive. Because of its large size, it may not show up immediately if your CPU asks you to open any application, software, or file you currently need. It’s slow, so RAM has to work instead. Although it is small in size, it will immediately display the CPU command instead of the hard drive. RAM will store important data from your application and output it immediately if you need to.
For example, if you are playing a game, you will not be able to play on a single large hard drive. The game will be 1 frame per minute. When you start the game, you will see LOADING. At that point, the RAM is being transferred from the hard drive to the data drive for the game you are about to play, and the RAM and hard drive will work together to run the game. If you have a yard, a large warehouse, and a lot of belongings, it will take a Fri time to find and pick up when you need something.
Or you may need to buy something that you urgently need. The occasional outlet can be easily found if you move it to a smaller one near the gate, rather than in a large warehouse. A large warehouse is like a hard drive and a small store is like RAM.