What is the primary role of ribosomes in a cell, and where are they found?

The primary role of ribosomes in a cell is protein synthesis (translation). They are responsible for reading the messenger RNA (mRNA) sequence and assembling amino acids into polypeptide chains according to the genetic code. Ribosomes are found either free in the cytoplasm or bound to the Rough Endoplasmic Reticulum (RER) or the nuclear envelope.