The force exerted by the molecule on the surface of a liquid are attracted only towards the sides and downward that its surface behave like an elastic film.

Water is poured on a taro leafWater is poured on a taro leaf

Water strider walking on water

Presence of impurities either on the surface or dissolved in it.

Highly soluble substance increases the surface tension.

Sparingly soluble substance reduces the surface tension.

Surface tension of a liquid decreases with increase in temperature.