SSD stands for ‘Solid State Disk’: a form of storage that doesn't have any moving parts. Traditionally, the hosting industry has used HDD (Hard Disk Drive) for its storage solutions, which does have moving parts. In fact, a lot of hosts still use them. Because SSD drives don't have any moving parts SSD hosting can process information much quicker than their HDD counterparts and are much more reliable. Some hosts try to save money by only using SSD hosting for their cache. This lets them advertise that they use SSD, when in fact if someone visits an uncached page they hit the much slower HDD drive. At 20i all our customers are hosted using the latest top-spec Samsung SSD drives. It's one of the reasons why we’re a fast web host.