A transit peptide that, when fused to a protein, acts to transport that protein into chloroplast(s) in a plant. Once (both are) inside the chloroplast, the transit peptide is cleaved off the protein and that protein is then free (to do the task it was designed for).
For example, the CP4 EPSPS enzyme in genetically engineered glyphosate-resistant soybean [Glycine max (L) Merrill] is transported into the soybean plant’s chloroplasts by the CTP known as “N-terminal petunia chloroplast transit peptide.” After (both) reach the chloroplast, the CTP is cleaved and degraded, so the CP4 EPSPS is then free to do its task (i.e., confer resistance to glyphosate).