It's a common syndrome - one day your site is happily indexed, and the next it's gone for a walk with a one way ticket. The questions that you no doubt are asking yourself are probably not the most logical or well thought out. Perhaps you've already tried contacting Google and found it hard to get specific advice on your site? Today is your lucky day, we have compiled a checklist of key tests that are easy to carry out in order to give a good idea why your site has dropped out.

The Not-to-worry questions
Mirror, mirror, on the wall
Go and check if your site shows up on search.aol.com. AOL use a slightly different version of Google's index to the one you normally see in most cases. If your site can be seen in AOL, then you don't have to worry yet, you may be seeing test / trial results which are regularly sent out by Google to selected areas, particularly in competitive keywords. If your site is fewer than 6 months old it is much more likely to be affected, according to our observations.

What can I do now?
The fact that you dropped out at all is an indication that your site is near the edge of indexability. Faced with this, you would do well to follow good practice to increase your site's spider allure. Go ahead now and write one new article for your 'resources' section, and delete a few links to sites that just aren't relevant at all.
Fallen like a stone
Every day Google's index seems to change subtly. Some sites soar, some sites plunge. Few actually drop out. Are you right in saying that your site has disappeared? Perhaps one of the simplest tests is to go to Google, and type site:mydomain.foo - where 'mydomain.foo' is your website domain name. If you get results back, even just one, then you certainly are not a lost cause yet.

I'm not even there with site: test - what can I do?
Your site is looking a bit more worrying. Let's run through some more tests and try to work out if your site really is in trouble - and how to fix it if it is.

The Kiss-of-Death Questions
Note: To trigger these, in most cases, it will have taken some action on your part... they won't have happened all on their own!

Headers
Let's check your headers. When Google comes to your site, it will read your headers. Sometimes, these are wrong. You really want a header in the 200 series. A 300 series header may do at a push. A 400 series header is bad bad news.

How to check your headers
Open a shell (linux) or from windows, using the Start Menu, select Run, and type 'cmd' - no quotes (or 'command' if cmd doesn't work).

Type 'telnet yourdomain.foo 80' (no quotes, yourdomain.foo is your domain name). This will open a direct telnet to your internet port (port 80). Now, let's read your home page, which is identified only as /. Type: HEAD / HTTP/1.0 Now press Enter twice, and have a good look at the returned data. Within the returned data should be one of the codes listed here. Once you've identified the code you've got, read on.

My code starts with 2 (200 OK, etc)
Great news, in a way. The 200 series are quite good for Google, they show that the data that is being given is OK, just fine, and it's being sent. There's not likely to be a problem with one of these headers.

My code starts with a 3 (301 Moved Permenantly, 302 Found, 304 Not Modified, etc)
First, if your code is 304, don't worry, it just shows that your page has not changed, and you don't have to worry about the headers. Otherwise, you may be in trouble. If your header says 302, this is a redirection. It is a temporary redirect to another page, and Google will not cache the redirection. Is the page actually moved? Well... you should have a 301 header. Very few internet solutions require the 302 header. Best change that to a 301.

My code starts with a 4 (400 Bad Request, 401 Unauthorised, 404 Not Found)
You really should fix that. So far as Google (and many browsers) is concerned, this page is just a 'Page Not Found' or similar error page, and no self respecting spider wants to keep a record of the content of such pages. This is a common problem when people use 'custom 404 content systems'. The header MUST be changed to 200 OK!

Robots Exclusion
As much as it may amaze you, some people actually want to get rid of spiders. How? There is a standard which allows for this. Have a look at yourdomain.foo/robots.txt and have a good read. Was it there? If so... did you see the word 'disallow'? If so you may well be on the trail of your problems. We advise to first rename the file to robots.old, and then read up on the file format. If you can't understand how to write the robots.txt, you're probably a lot better off without it. There's another related possibility - do have a look at your page source - and do you see the words 'noindex' or 'nofollow' in the section? If you do, you really have to remove those as well.