What is picric acid? How is it prepared from phenol?

Hint: The compounds made up of carbon and its derivatives are known as organic compounds. Picric acid is also an organic compound having three nitro and a hydroxyl group attached on the benzene ring.

Complete step by step answer:
Picric acid is an organic compound. The IUPAC name of picric acid is $2,4,6 - trinitrophenol$ . It is an acidic phenol and an explosive compound also .
Picric acid:

Picric acid is basically prepared from phenol by reacting phenol with concentrated sulphuric acid and concentrated nitric acid. The nitro groups from nitric acid attacks on ortho and para positions which is the best suitable and stable position for the newly formed compound which is picric acid.
Reaction:

Picric acid is produced in two steps. The first step contains the formation of phenol sulphuric acid which on further reacting with conc. Nitric acid results in $2,4,6 - trinitrophenol which is also known as picric acid.

Note:
Picric acid is a toxic organic compound which is soluble in hot water, alcohol, ether, benzene and acetone. The explosive power of picric acid is higher and comparable to that of TNT.