What? Gravity is weak? Then how am I not floating right now? This has to be a joke.
Gravity is one of the four fundamental forces in our universe. The others are electromagnetic, strong nuclear, and weak nuclear forces.
Gravity is the oddball in this group. It is also preventing the completion of the unification equation.
While the other forces, besides E-M, have relatively short ranges, gravity does not. Gravity has infinite range, and has a bigger effect over range than other forces. Gravity is pulling the Milky Way and Andromeda galaxies together at this very moment. Gravity pulls everything together due to its range and the size of the objects being moved, but it pales in strength to the other forces.
When put on the same scale as all the other forces, the force of gravity is an afterthought. At the same levels, E-M forces are magnitudes stronger than gravity. Strong and weak nuclear forces affect individual particles much more than gravity does.
For example, the magnitude of E-M force between two hydrogen molecules is an undecillion times stronger than gravity.
Science hasn't really given a definitive answer, but we do know that the universe as we know it wouldn't exist without this weak force, because neither would we.