Cloning is the process of creating an identical copy of an original. A clone in the **biological** sense, therefore, is a single **cell** (like **bacteria**, **lymphocytes** etc.) or multi-cellular **organism** that is **genetically** identical to another living organism. Sometimes this can refer to "natural" clones made either when an organism **reproduces asexually** or when two genetically identical individuals are produced by accident (as with **identical twins**), but in common parlance the clone is an identical copy by some conscious design. Also see **clone (genetics)**. The term clone is derived from κλων, the **Greek** word for "twig". In **horticulture**, the spelling clon was used until the twentieth century; the final e came into use to indicate the vowel is a "long o" instead of a "short o". Since the term entered the popular lexicon in a more general context, the spelling clone has been used exclusively.
However, the success rate has been very low:
**Dolly** was born after 276 failed attempts; 70 calves have been created from 9,000 attempts and one third of them died young; **Prometea** took 328 attempts, and, more recently, **Paris Texas** was created after 400 attempts. Notably, although the first clones were frogs, no adult cloned frog has yet been produced from a somatic adult nucleus donor cell.
Human cloning is the creation of a
**genetically** identical copy of an existing, or previously existing **human** or growing cloned **tissue** from that individual. The term is generally used to refer to artificial human cloning; human clones in the form of **identical twins** are commonplace, with their cloning occurring during the natural process of reproduction.