Unlike regular filesystems, which are designed to manage persistent file data backed on to a storage device, the kernel implements various special filesystems that manage a specific class of kernel in-core data structures. Since these filesystems do not deal with persistent data, they do not consume disk blocks, and the entire filesystem structure is maintained in-core. Presence of such filesystems enables simplified application development, debugging, and easier error detection. There are many filesystems in this category, each deliberately designed and implemented for a specific purpose. Following is brief description of a few important ones.