Intutitive

A great laymen book on inflation is "The Inflationary Universe" by Alan Guth, who is one of the inventors of inflation.

Concrete

• http://www.damtp.cam.ac.uk/user/db275/TEACHING/INFLATION/Lectures.pdf

Abstract

• The Inflation Debate, by Paul Steinhard
• https://blogs.scientificamerican.com/observations/a-cosmic-controversy/
• https://www.quantamagazine.org/taking-stock-of-the-big-bang-theory-of-inflation-20150130/
• http://backreaction.blogspot.de/2017/10/is-inflationary-universe-scientific.html
• http://backreaction.blogspot.de/2017/10/i-totally-mean-it-inflation-never.html

Why is it interesting?

Inflation is a framework the was invented to explain the cosmological flatness problem, i.e. to explain why spacetime is so flat, and to explain why there are no magnetic monopoles.

History

A great discussion can be found here: https://telescoper.wordpress.com/2017/07/13/the-early-stages-of-cosmic-inflation/amp/

Criticism

• See The Inflation Debate by Paul J. Steinhardt