Invisible on the listing page

Is there a way to make something invisible on the listings page, but still visible to a search.

I am using the basic search command:


<form method="POST" action="/jobs/employerlist.php">
<input type="text" name="title_keyword" value="JobSearch" size="10">
<input type="submit" name="submit" value="Search">
</form>

What I'd like to do is have keywords that would be included in a search, but would not show up as text on the page.

Is there a simple way to do this (for a new php person).

Also, is there a way to search an entire site, adding all of the listings pages to one search.

Finally, is there a way to do it, so that a user can select the section they want, using something like I have below:

<form method="POST" action="/SOMETHING_HERE.php">
<input type="text" name="title_keyword" size="10">
<select size="1" name="Selection">
<option>Jobs</option>
<option>Events</option>
<option>Pubs</option>
</select>
<input type="submit" name="submit" value="Search">
</form>

Thanks,

Joe