Clones are segments of code that are similar according to some definition of
similarity. (Ira Baxter, 2002)
A software clone is a special kind of software duplicate. It is a piece of software
(e.g., a code fragment) that has been obtained by cloning (i.e., duplicating via
the copy-and-paste mechanism) another piece of software and perhaps making some
additional changes to it. This primitive kind of software reuse is more harmful
than it is beneficial. It actually makes the activities of debugging, maintenance
and evolution considerably more difficult.
clone detection
The activity of locating duplicates or fragments of code with a high degree of
similarity and redundancy.