Google Webmasters Tools is a superb tool for webmasters to view all sorts of useful data such as on-page site issues, sitemap problems, download times and also 404 errors. 404 Errors can sometimes cause some confusion among non-technical people and so in this article I will explain the fundamentals of what they are, what impact they may have and how to deal with them.What Is a 404 Error?Ok so if we start at the question of what exactly is a 404 error, then we can begin to see why these are a potential concern for webmasters. A 404 error is in very simple terms, Google Bot saying ‘I was trying to find a web page but it seems the content is no longer there…darn’. Then it reports back to Google telling them that a 404 error has occurred and this is how it appears in your webmasters tools.What Can I do About This?If you did have a web page of content on a service that you used to have, however have now stopped providing that service, then you might have taken that web page down, which is perfectly normal. From a ‘best online practice’ point of view we need to 301 redirect that web page to avoid a 404 error.A 301 redirect is your website telling Google Bot ‘Hello Google Bot, the content you are looking for is no longer here but has now moved to another place i.e. your other services page’. Remember if you are going to 301 redirect to another page on your website, make it as relevant as possible and not just to redirect to your homepage!Are There SEO Benefits From This?In some cases there are some pretty good SEO benefits from doing this especially if you have links to those web pages that you are taking down, as a 301 redirect passes on all link value to the new web page you choose to 301 redirect to.It is worth noting though that many web pages don’t have inbound links to them and so there would be next to no SEO benefit from a 301 in these instances. In this case best practice would dictate you 301 redirect to the next most relevant page, however it is not essential.Is This Critical To Ranking Well?If we get down to the real question, is this a critical ranking factor to success on Google, the answer is no it is not. There are many more important ranking factors to consider in ranking effectively on Google, however fixing 404 errors should be done periodically. Avoiding 404 errors is impossible especially on larger websites such as Ecommerce sites and search engines fully understand this fact.Quick Recap:- 404 errors means content is not where it used to be i.e. the web page has been moved.- 301 redirects is how you tell Google & search engines the content has moved and where to go instead.- There are SEO benefits to 301 redirects if the web pages have a good amount of links to them.- Redirecting 404 errors is not critical to your website ranking well on search engines but it is best practice.Of course there are occasions where to many 404 errors will negatively affect a websites performance; however these tend to be extreme cases where 404 errors are running into the thousands.