SSD stands for solid state drive and an SSD is the next generation of the hard drive. People sometimes call SSDs solid state discs even though these gadgets have no discs or any other moving parts, making the more reliable and potentially much faster than conventional hard drives.
SSDs use integrated circuits rather than magnetic or laser storage to preserve data persistently. Upgrading to an SSD is a good move and easy to do. Keep your data safe on an SSD.