This is from the beginning of chapter one of "The Island - An anthology of the Buddha's teachings on Nibbana" by Ajahn Pasanno and Ajahn Amaro:
WHAT IS IT ?
Nibbana (Nirvana in Sanskrit) is a word that is used to describe an experience. When the heart is free of all obscurations, and is utterly in accord with nature, Ultimate Reality (Dhamma), it experiences perfect peace, joy and contentment. This set of qualities is what Nibbana describes. The purpose of this book is to outline the particular teachings of the Buddha that point to and illuminate ways that these qualities can be realized. From the Buddhist viewpoint, the realization of Nibbana is the fulfillment of the highest human potential – a potential that exists in all of us, regardless of nationality or creed.
(continues at the link)
https://www.dhammatalks.net/Books9/Ajah ... Island.pdf

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