The technical term ,Well indicates in Nail terminology, one of the parts that compose a tip (an artificial nail used while doing Gel Nail Extensions).
Each tip is in fact formed by two main parts: a thicker part which is the length of the rebuilt nail and a more thinner and semi-transparent part called Well, which will adhere to the surface of the natural nail.In the well area of the tip,the nail glue will therefore be applied before placing the tip on the natural nail.