sampling is quoting phrases or sounds from other sources.
any good music/electronic store should have a selection of sampling cds.
these cds contain recordings made by professional musicians that can be used by anyone who buys the cd in their own recording.
with digital recording becoming more sophisticated, it's quite easy to make a song around sampled sounds, using very little original input.
what people may be objecting to in this thread is the use by professional musicians of others' tunes, chord progressions, guitar riffs etc. in their own songs. this can seem like plagiarism.
i repeat that it's not that simple, and that sampling is the latest incarnation of the time honoured practice of arranging. perhaps because in sampling the sound is often identical to the original it appears the new version is cashing in on the old.
but often reggae, hip hop or rap versions of an old song are really creative arrangements.
you can't blame sampling for that other time honoured practice, stealing!