A while back all backlinks were good, and webmasters struggled to get as many as possible, as quickly as possible. Then black hat SEO came along, as some “experts” with shady practices quickly realized the potential of this market segment, and soon there were paid links and link farms everywhere – to the point that a new website with almost no content could skyrocket in search results overnight, taking over many legitimate, long-established sited on the same topic.And now search engines have to fight to stop this trend. It's going to be a long battle, and there will be collateral victims in the process – inexperienced webmasters who fell for the black hat hype, or who made mistakes without knowing the ins and outs of this business. And, without a doubt, there will always be ways to cheat search engines, and some creative entrepreneurs will always find such ways – even if in some cases it may take more effort than legitimately increasing a site's ranking with acceptable, ethical methods.
The best known, and most discussed attempts to cut the number of paid backlinks were, of course, Google's famous algorithm updates, Panda and Penguin, but most other search engines have taken similar steps. Cute naming strategies from the market leader, but a lot of webmasters have had nightmares with pandas and penguins eating into their rankings during the past months.
While the updates have helped clear up some paid backlinks and link farms, there's still a long way to go, and now search engines admitted the need for human input, along with algorithm changes. Therefore, both Google and Bing introduced new tools allowing the webmasters to reject, or disavow backlinks, if they notice a spamming problem.
For most webmasters, this should present no problem at all, and it's very likely that 90% of them won't ever use this tool. The other 10% however cheered the announcement, as it does introduce a lot more control over a site's situation than ever before. There have been reports of dodgy practices in the past, with webmasters trying to take down competition by using black hat SEO for their competitors' websites. Now, this shouldn't be possible anymore.
There are, of course, certain risks involved in using this tool, and one may accidentally remove legitimate backlinks – and that's the last thing you want to do, considering how difficult it is to obtain those in the first place. As with everything else, if it's not broken, don't try to fix it – there's no point in toying around with this tool, if you have no reports of spamming or unnatural links, as you may end up doing more harm than good.
The most important thing to remember from all this is a very simple one: all these efforts put into improving the best practices in this area indicate that backlinks will remain one of the most important factors used by search engines when they evaluate a website. Therefore, the efforts to obtain them in legitimate ways should intensify, as they can only become more and more valuable as time goes by.