If you didn’t know, replacing your Mac’s HDD or traditional disk and spindle hard disk (with moving parts) with an SSD can bring about amazing performance improvements. On a HDD, the motor and spindle spin every time your Mac needs files or folders to access. If those files and folders are all over the place on your Mac, it is just a lot of spinning to find and access the data. This is particularly the case if your disk is defragmented. In other words, if you have a plate with your vegetables and meat very far away from each other, it is going to take you just a little extra longer to get a bite sized cut of meat and a vegetable like a bean in your fork, as opposed to when they are almost together on your plate.
In an SSD however, everything is digital. There is no moving parts like a motor and spindle and everything is accessed instantaneously.
Replacing your Mac’s HDD with an SSD is not that difficult either. Buy a SSD that will easily accommodate your OS partition space and then have about 40% of the disk space left over as free disk space. Then, use the CD provided to install a cloning software that will clone your Mac OS partition onto the SSD. You could also do a fresh install of your Mac OS and backup your user data from Time Machine as well. The choice is yours. Just make sure to test the new SSD as your boot up drive before swapping it out permanently for your HDD. That way, if something is wrong with your SSD cloning, you will still have a working OS from your HDD to fix the cloning issue on your Mac’s new SSD that you are trying to attempt. Replacing your Mac’s HDD with an SSD is one of the best ways to speed up your Mac, as explained in http://www.whyismymacsoslowallofasudden.com