TRIM/UNMAP. A common problem with SSDs is that a host file system could erase free data but didn't have a way of telling the storage device it no longer needed that data. The TRIM/UNMAP interface lets the SSD clear the LBA (logical block addressing) entries in the FTL, giving it more free space to use in garbage collection and reducing write amplification. OS/X, Microsoft Windows, and Linux have implemented TRIM.
FreeBSD has TRIM support, too.