In politics (and particularly in international politics), soft power is the ability to co-opt rather than coerce (in contrast with hard power).
It involves shaping the preferences of others through appeal and attraction.
Soft power is non-coercive, using culture, political values, and foreign policies to enact change.
It is the capacity to coerce another to act in ways in which that entity would not have acted otherwise.
A military invasion is hard power.
Economic sanctions are hard power.
In contrast, coopted or soft power is the capacity to persuade others to do what one wants.
Soft water is water that has had dissolved ions, with the exception of sodium ions, removed and has an ion concentration of 17mg/L or less.
Rainwater is considered soft water; water becomes hard as it travels through the ground and absorbs minerals.