1.A clone is a population of identical cells or DNA molecules descended from a single progenitor.

Cloning is to make many copies of the same thing. The cloning we talk nowadays is most of the time the recombinant DNA technique in which specific cDNAs (complimentary DNA copied from mRNA by reverse transcriptase) or fragments of genomic DNA, are inserted into a cloning vector (an autonomously replicating genetic element used to carry a cDNA or fragment of genomic DNA), which is then incorporated into cultured host cells and maintained during the growth of the host cells.

There are also two other types of clones called reproductive and therapeutic cloning respectively. You can get more information by going to cloning.

It is hard to know what those people think about cloning themselves. Ego? Curiosity? Adventure? Making a useful body part for later use? Hard to say. Maybe we should ask someone who wants to clone himself.