What is Android's file system? [closed]

It depends on what filesystem, for example /system and /data are yaffs2 while /sdcard is vfat.This is the output of mount:

rootfs / rootfs ro 0 0tmpfs /dev tmpfs rw,mode=755 0 0devpts /dev/pts devpts rw,mode=600 0 0proc /proc proc rw 0 0sysfs /sys sysfs rw 0 0tmpfs /sqlite_stmt_journals tmpfs rw,size=4096k 0 0none /dev/cpuctl cgroup rw,cpu 0 0/dev/block/mtdblock0 /system yaffs2 ro 0 0/dev/block/mtdblock1 /data yaffs2 rw,nosuid,nodev 0 0/dev/block/mtdblock2 /cache yaffs2 rw,nosuid,nodev 0 0/dev/block//vold/179:0 /sdcard vfat rw,dirsync,nosuid,nodev,noexec,uid=1000,gid=1015,fmask=0702,dmask=0702,allow_utime=0020,codepage=cp437,iocharset=iso8859-1,shortname=mixed,utf8,errors=remount-ro 0 0

and with respect to other filesystems supported, this is the list

nodev   sysfsnodev   rootfsnodev   bdevnodev   procnodev   cgroupnodev   binfmt_miscnodev   sockfsnodev   pipefsnodev   anon_inodefsnodev   tmpfsnodev   inotifyfsnodev   devptsnodev   ramfs         vfat         msdosnodev   nfsdnodev   smbfs         yaffs         yaffs2nodev   rpc_pipefs

By default, it uses YAFFS - Yet Another Flash File System.

Most answers here are pretty old.

In the past when un managed nand was the most popular storage technology, yaffs2 was the most common file system. This days there are few devices using un-managed nand, and those still in use are slowly migrating to ubifs.

Today most common storage is emmc (managed nand), for such devices ext4 is far more popular, but, this file system is slowly clears its way for f2fs (flash friendly fs).

Edit: f2fs will probably won't make it as the common fs for flash devices (including android)