Why is infinity the lower limit when deriving gravitational potential energy?

[Miraj Kayastha]

Why is infinite kept as a lower limit in the derivation of gravitational potential energy? Shouldn't the lower limit be smaller than the upper limit?


http://hyperphysics.phy-astr.gsu.edu/hbase/gpot.html

 

[Mr-R]

GPE is the energy needed to bring the object from infinity to r.