Correct spelling, explanation: essential is an adjective made from the noun essence. If you’re wondering why it has to be spelled with the double -s, the role is simple: a derivative must always accord with its root. In this case, the root is essence with two -s. Therefore, the only right version is essential, not esential.

Definition of essential:
adjective, basic and fundamental
When you’re preparing for an exam, it’s essential not to study a few hours before it.
I think love is an essential part of life.

Incorrect spelling, explanation: when deriving a word, one must always look at its root. In this case, it’s the noun essence. We can’t change the spelling of a basis, so esential is incorrect. Essential is an adjective made of two elements: essent + -ial. The -c consonant was changed into -t. The suffix -ial is used after some roots to form adjectives from nouns, with the meaning relating to, of the kind of. The only correct spelling of this word is essential.

Incorrect spelling

Incorrect spelling

Incorrect spelling

Incorrect spelling