Easily identifiable traits are referred as markers. The markers are of three types, viz. morphological markers, biochemical markers and DNA based markers.

Markers are typically small regions of the DNA, which shows the sequence polymorphism in different individuals within a species.

These are defined below:

1. Morphological markers: These are related to shape, size, color and surface of various plant parts.

2. Biochemical marker: Such markers are related to variation in protein and amino acid banding patterns.

3. DNA markers: Typically small regions of DNA showing sequence polymorphism in different individuals with in a species, e.g. SSR, RAPD, AFLP, SNPs etc.