What is the biggest transformation (change) that happens to Piper Kerman in Orange is the New Black?

Orange is the New Black: My Year in a Women's Prison (2010) is a memoir by Piper Kerman. The novel is significantly less violent compared to the adapted television series, which is largely fictitious.
In the novel, Piper Kerman's transformation is gradual as she becomes acclimatized to the realities of prison life. In the ten years between her affiliation with a drug lord and imprisonment, Piper lives a normal and comfortable life. She has many family members and friends who support her throughout her year of imprisonment. Piper has an uncomfortable start to her prison sentence when she is invasively strip searched.
Her prison sentence is relatively uneventful—with the exception of an incident when she accidentally takes a screwdriver and disposes of it in a dumpster so as to not be caught in possession of a deadly weapon.
Overall, Piper's biggest change is adjusting to the realities of prison life with its strict rules, regulations, and required work duties.