Surface tension can be explained in given possible ways:

(i)   The property of a liquid on account of which it tends to keep minimum number of molecules in its free surface is described as surface tension.

(ii)  The characteristics of a liquid, on account of which it leads to minimize it's free surface area, is called as surface tension.

(iii)  The work, required to be done in increasing the free surface of a liquid by unity at constant temperature, is described as surface tension.

(iv) The force operating per unit length of an imaginary line drawn on the free liquid surface at right angles to the line and in the plane of liquid surface is described as surface tension.