Two kinds of tap, two different repairs, and one wasted afternoon if you guess
Telling them apart
A tap that turns through about a quarter turn is ceramic. One that needs several turns and gets stiffer is a washer type.
Washer taps
Replace the washer and, while it is apart, look at the seat. A pitted seat makes a new washer fail within weeks.
Ceramic taps
Replace the whole cartridge; they are not serviceable. Take the old one to the merchant because sizes vary and photographs do not help.
