Some search engines don't record extremely common words in order to save space or to speed up searches. These are known as "stop words?."

Stop words are obstacles in Speedining the Searches

Some search engines store every word on a web page but they don't search for certain ones to save time. Consider a search for:

the piano player

The search engine has to make three runs to find matches (again, this is oversimplified).

First it looks for all matches of the, then all matches of piano, then all matches of player.

Chances are, just looking for the last two words is enough to find relevant pages. So to save time, the search engine excludes searching for a select number of small words. It won't "stop" to look for them.

List of Stop words:

I
a
about
an
are
as
at
be
by
com
de
en
for
from
how

in
is
it
la
of
on
or
that
the
this
to
was
what
when
where

who
will
with
und
the
www