What is the purpose of different Android partitions

-- [b]Boot partition[/b] stores the Android kernel. If this partition is empty, the LK bootloader will enter the fastboot mode.
-- [b]System partition[/b] contains the Android user interface and all the pre-installed system applications.
-- [b]Data partition[/b] contains the user's data- contacts, messages, user installed applications, settings etc..
-- [b]Tombstone partition[/b] saves the ramdumps of any sub-system on crash.
-- [b]Cache partition[/b] stores the frequently accessed data and application components.
-- [b]Persistent partition[/b] stores any "persistent" data which does not get lost even on a factory reset. MAC address as an example.