We're not talking your untimely end, of course, but the slow death of your website! Maybe you're all too familiar with the scenario?

Website ranks on page one of your favourite search engine. Before you can give yourself a much-deserved slap on the back it slips a little, then slides some more. Page one is just a distant memory as page two gives way to page three... Finally you sink so low the only way left is up.

So what's gone wrong? The website looks good, has great content and you've correctly identified the market niche. There are appropriate keywords in the 'title', 'alt' and 'H1' and 'H2' tags, and you've also sprinkled them throughout each page at a reasonable density level, with the odd 'b' tag thrown in for good measure.

The truth is you've done nothing wrong, at least in terms of on-page optimization. Nowadays, though, it's very much less than half the battle. Very much less. Once upon-a-time, before Google and PageRank, on-page optimization was all you needed to rank highly in the search engines. Not any more.

Now 'off-page' optimization, or links to be more precise, is everything. And without links, either one-way or reciprocal, your link popularity stays at zero and you won't rank for any competitive keyword or phrase.

The concept is devilishly simple from the search engine's point of view. Every link is a thumbs-up or 'vote' for the page it points to. In simple terms, the more votes the better the page ranks.

Well, not quite, because there are good links and there are bad links and learning to spot which is which can make all the difference.

The best links are one-way links. Other websites link to you because your site is so full of interesting and informative content they simply have to tell the rest of the world about you.

Great if you can get them but for most of us who don't have a site to rival CNN or the BBC, such spontaneous linking is a rarity.

Of course, if you've a pile of spare cash lying about then you can buy one-way links instead. But it'll cost and if Google and the other search engines even suspect that that's what you're doing - buying links in order to inflate your link popularity - then watch out. You will be tagged as a spammer and suffer the consequences. Not worth the risk!

So, for the vast majority of us, reciprocal links is our only option. You know how it goes - A links to B in return for B linking back to A. And no matter what you may have read to the contrary, reciprocal linking does still work.

The problem is you've got to exchange links with a lot of other websites in order to make an impact, especially if your field is a competitive one. And the site or page your link is on has to loosely match the theme of your website for maximum benefit.

Make sure, too, the page doesn't have too many other links on it. Around 10 to 20 is ideal, 30 or so is fine but anything higher than that then be cautious. A page with dozens of links on it is nothing more than a 'link farm' and should be avoided. Google and the other search engines hate them.

Reciprocal linking is a time-consuming process, often frustrating but worth the hard work. It will pay handsome dividends long term so don't ignore it. Link or die, it really is that simple.

John Donaldson is the owner of reciprocal-links.co.uk, a free search engine which takes the frustration out of finding relevant link partners.