Here's why:

* Diploid means "having two sets of chromosomes".

* Chromosomes are structures in the nucleus of a cell that carry genetic information in the form of DNA.

* Pairs indicate that each chromosome has a corresponding counterpart (its homolog) carrying similar genetic information.

Most cells in the body of multicellular organisms are diploid. The only exceptions are gametes (sperm and egg cells), which are haploid (having only one set of chromosomes).