Yahoo! provides "presence" for our Yahoo! Messenger ID statuses, this nifty little bit of html allows our Yahoo! Messenger ID status (online/offline) to break out of the standard availability on our Yahoo! Profile or 360° pages and onto our personal homepage/s, forum profiles, email signature files etc, in fact anywhere that html is permitted. Simply edit the code they provide with your own messenger id then cut and paste the html into the desired location.

If you're currently logged into your Yahoo! account when you access Yahoo! Add Presence your cut and paste code will be all set to go with your ID automatically inserted and available for use, if you're not logged in or which to use an alternate ID then you'll be presented with their stock standard example html code....

<a href="http://edit.yahoo.com/config/send_webmesg?.target=dairyman88&.src=pg">
<img border=0 src="http://opi.yahoo.com/online?u=dairyman88&m=g&t=2&l=us"></a>

in their example the user ID is dairyman88, all you have to do to personalize the code is replace dairyman88 with the ID you wish to use, this needs to be done in two places
the link....
<a href="http://edit.yahoo.com/config/send_webmesg?.target=dairyman88&.src=pg">
and the image....
<img border=0 src="http://opi.yahoo.com/online?u=dairyman88&m=g&t=2&l=us">

so using my Yahoo! Messenger ID beegeeknz, my cut and paste code (once edited :) looks like this....
<a href="http://edit.yahoo.com/config/send_webmesg?.target=beegeeknz&.src=pg">
<img border=0 src="http://opi.yahoo.com/online?u=beegeeknz&m=g&t=2&l=us"></a>

which generates the following display by default....


so if I'm online you'll see... and offline will be...

which is kinda cool but personally I find that size a littlebig and in your face, but all is not lost, there is a tweak which you can use that gives 2 other size/display choices...

and...


both these are available from Yahoo! (not an external site or script) all you have to do is change the image code they provide...
<img border=0 src="http://opi.yahoo.com/online?u=URMESSENGERID&m=g&t=2&l=us">
will generate 2 this style

<img border=0 src="http://opi.yahoo.com/online?u=URMESSENGERID&m=g&t=1&l=us">
will generate 1 this style

<img border=0 src="http://opi.yahoo.com/online?u=URMESSENGERID&m=g&t=0&l=us">
will generate 0 this style

so if I wanted to use the smallest display my code (with my ID) would look like this...

<a href="http://edit.yahoo.com/config/send_webmesg?.target=beegeeknz&.src=pg">
<img border=0 src="http://opi.yahoo.com/online?u=beegeeknz&m=g&t=0&l=us"></a>

which generates this....



For your Online Status to visible to others you need to make sure that the presence option is enabled in your Profile, you can access this a variety of ways, either directly from in Yahoo! Messenger via Messenger > My Account Info > Create/Edit Profiles, or Messenger > My Profiles > Create/Edit My Profiles or you can take the direct approach and just head to http://edit.profiles.yahoo.com/config/edit_identity, once you're there look out for the following...

the box must be unchecked for your status to be publically available, check out Yahoo!'s What does "online status" mean? if you're unsure what it's all about. Do remember if you're juggling your status, visibility or using stealth settings then you will need to be aware that where ever your online presence is posted/placed (your own personal homepage, signature files etc) then it's visible to ALL the general public regardless of if you have them "blocked" or on "ignore" via your friends list. Long and the short of that is, if you're having problems online with someone being a rat bag etc then DISABLE this feature immediately via your Profile settings as with it enabled, if your status is set to online they WILL be able to see you're logged onto Yahoo!.

Summary of Links:
Yahoo! Add Presence ~ http://messenger.yahoo.com/addpresence.php
Yahoo! Profiles ~ http://profiles.yahoo.com/
Yahoo! 360° ~ http://360.yahoo.com

if you're after a status indicator a little different to the ones offered by Yahoo! then swing by http://www.onlinestatus.org/ for alternatives.