This is wear of the gristle bearing surface of the ball and socket joint of the hip, until the underlying bone grinds against bone.
It causes pain, often in the groin, it can radiate down to the knee (of the front and often on the inside of the leg) and occasionally the inside of the shin. The pain is worse when walking, can be bad at night. Typically patients experience difficulty in getting down to thier toes on the affected side, for example putting socks on or cutting thier toe nails.
Pain is worse at the end of the day. The hip can be stiff and painful for the first half an hour in the morning.
Hip arthritis limits most activities. The condition comes on gradually, patients often cope by avoiding certain activities, for example walking for pleasure. They will park the car very near to the shops, sometimes they will walk somewhere and not be able to get back because of pain. Thier friend or relatives will point out that they are limping.