Essential amino acids: Cannot be synthesized by the human body — must come from diet. 10 for children, 8 for adults.

Mnemonic "PVT TIM HALL": Phenylalanine, Valine, Threonine, Tryptophan, Isoleucine, Methionine, Histidine (essential for children), Arginine (essential for children), Leucine, Lysine.

Non-essential: Glycine, Alanine, Serine, Cysteine, Tyrosine, Proline, Aspartate, Glutamate, Asparagine, Glutamine. The body synthesizes these from other metabolic intermediates.

Special cases: Tyrosine is synthesized from phenylalanine (so technically non-essential, but becomes essential if Phe is deficient). Cysteine requires methionine as a sulfur source.

For JEE: The most commonly tested fact is simply knowing which amino acids are essential. The mnemonic PVT TIM HALL covers this completely.