[R] Difference between loops and vectorization

[Santosh Srinivas]

Hello R-helpers,

A fundamental question ...I'm trying to understand the differences
between loop and vectorization ... I understand that it should be a
natural choice to use apply / adply when it is needed to perform the
same function across all rows of a data frame.
Any pointers on why this is so? Unable to find the right reading place
on the WWW which explains the concept.

Thanks for your help.
S