Define Inflation theory

In physical cosmology, cosmic inflation, cosmological inflation, or just inflation, is a theory of exponential expansion of space in the early universe. The inflationary epoch lasted from 10-36 seconds after the conjectured Big Bang singularity to sometime between 10-33 and 10-32 seconds after the singularity.

Inflation theory is a theory of exponential expansion of space in the early universe

Explanation:

The term inflation means expansion and in Physics it refers to the explosively rapid expansion of space-time that occurred a tiny fraction of a second after the Big Bang. According to Big Bang theory the universe expands relatively gradually throughout its history. Inflation theory was developed around 1980 to explain several puzzles with the standard Big Bang theory.