/etc/fstab format?

please see

http://en.wikipedia.org/wiki/Fstab
http://www.debianhelp.co.uk/fstab.htm

which part is not clear?

/etc/fstab is a file, divided into records (lines), which are divided in fields (separated by white space) the first field is the file system device file or UUID (hardware identification). The second field is the mount point (a regular old directory) where the file system is mounted. The third field is the file system type (msdos, iso9660, nfs, ext4, auto, etc) The fourth field are mount options, divided by commas. The last 2 fields determine if the file system will be checked by fsck automatically, and with what priority in relation to the other file systems. 0 0 means the file system will not be automatically checked. 1 1 will be checked, and will be first priority. 1 2 will be checked after 1 1.  

I can't understand what are files system devices (tmpfs)(devpts)(sysfs)? what they are there.?

tmpfs                   /dev/shm                tmpfs   defaults                  0 0
devpts                 /dev/pts                  devpts  gid=5,mode=620   0 0
sysfs                   /sys                        sysfs   defaults                    0 0
proc                    /proc                       proc    defaults                   0 0

Also is correct that the mount points should not world writeable for security reasons?

I can't understand what are files system devices (tmpfs)(devpts)(sysfs)? what they are there.?

tmpfs                   /dev/shm                tmpfs   defaults                  0 0
devpts                 /dev/pts                  devpts  gid=5,mode=620   0 0
sysfs                   /sys                        sysfs   defaults                    0 0
proc                    /proc                       proc    defaults                   0 0

Also is it correct that the mount points should not be world writeable for security reasons?