First-in, first-out (FIFO) page replacement algorithm: In FIFO page replacement algorithm, operating system has a list of pages in the memory. Whenever a new page comes it is put at the back of the list. The page at the front of the list is the one which is oldest in the memory. When a page fault occurs, the page from the front is removed and a new page is added at the back of the list.
Second chance page replacement algorithm: It is a modification of the FIFO page replacement algorithm. In this algorithm, instead of replacing the oldest page at once, its referenced bit is checked. If the referenced bit is 0 then it is replaced and if the referenced bit is 1, first the bit is cleared, secondly load time is reset to current time and then the page is put at the back of the list. Thus, the page is provided with a second chance and hence the name of the algorithm is second chance page replacement algorithm.
Clock page replacement algorithm: In this algorithm, pages are put in a circular list just like in a clock. On the occasion of a page fault, the hand which is pointing to the page is checked. If the referenced bit is 0 then the page is replaced with a new page at the same location and the hand is moved one position. If referenced bit is 1 then first it is cleared and then hand is moved one position. It is done until a page is found with referenced bit as 1.