On x86 processors not having paging features, like the Intel 80286, the LDT is essential to implementing separate address spaces for multiple processes. There will be generally one LDT per user process, describing privately held memory, while shared memory and kernel memory will be described by the GDT. The operating system will switch the current LDT when scheduling a new process, using the LLDT machine instruction or when using a TSS. On the contrary, the GDT is generally not switched (although this may happen if virtual machine monitors like VMware are running on the computer).