-> /proc/devices: 
    It contains the character and block devices
    with their major number.

-> Why character devices are called character devices?
    Because the read/write operation done is in size of
    byte.

-> Why block devices are called block devices?
    Because the read/write operation done is in size of
    block.

-> To read bytes of a devices
    use:
    hexdump /dev/<device_name> 

    to see only few bytes 
    Use:
    hexdump /dev/<device_name> | head

-> To create a new device file
    Use:
    mknod <device-name> <type of device 'c' or 'b'> <major-num> <minor-num>

-> /dev/*:
    this file basically contains virtual files which act as a 
    interface between the device driver in kernel space and
    the user space, which allow the control of the device from
    user space.

-> The link between the driver and the device file is made over
    the major and minor number of the device file rather than 
    name of the device file. So, if I associate a custom made
    device file with driver using same major and minor number.
    I can access the same device using that file.