Knuckles are the joints in the fingers that allow for bending and movement, playing a crucial role in hand dexterity and grip strength. Each finger has three knuckles, except for the thumb, which has two, enabling a wide range of motions necessary for everyday tasks like writing and gripping objects. However, they can be susceptible to issues such as arthritis and injuries from impacts or repetitive stress. Maintaining knuckle health through regular exercise and protection during activities can help preserve hand function and prevent discomfort.