A signal peptide is a short sequence of amino acids found at the beginning of a protein. It acts as a tag that directs the protein to its proper location within the cell, such as the endoplasmic reticulum or outside the cell. This sequence is typically removed once the protein reaches its destination. Signal peptides are crucial for the proper functioning of many proteins, especially those involved in secretion or membrane insertion. They are recognized by a cellular machinery called the signal recognition particle (SRP), which helps transport the protein to the correct site.