Explain with the help of examples FIFO algorithms?

FIFO policy: This policy easy removes pages in the order they arrived into the main memory. By using this policy we easily remove a page based upon the time of its arrival into the memory.

For illustration if we contain the reference string: 1, 2, 3, 4, 1, 2, 5, 1, 2, 3, 4, 5 and 3 frames (i.e. 3 pages can be into memory at a time per process) after that we have 9 page faults as demonstrated

If frames are raised say to 4 then no. of page faults also raises, to 10 in this case.