“Allways inform with redirect the search engines about changes to the URL or general site changes“
You will find that when you have a website there will be the need to change it. Mostly this is a matter of updating the content of a page to keep it fresh. Often this is simply a matter of adding pages with new content. These pages will be found by the search engines because the page is linked in some way to other pages on the site. No effort needs to be done by the webmaster to make this happen. Sometimes however you will need to change the name of the URL to better reflect the keywords you want to link to the page and in doing so improve the SEO ranking. In extreme cases, it can also be possible that the whole site name needs to be changed.
What happens then is that the bookmarks that people have created and also Google will point people in the wrong direction i.e. to the old location of the site. As this no longer exists they will get an Error 404 and not be very pleased about it. To avoid disappointing customers and to also not have Google believe the website is out of control you need to tell these users where the new location is. The best way to do this is by creating a redirect 301. This is a permanent redirect and tells the user where the new page is located. In order to have this redirect the old page must still be active and contain the information whereto the page is to be linked. In this way the built up value of the page can be retained. SEO-optimizers has seen many examples of especially large corporations which did not clean up after major site changes were carried out. As a result they lost a lot of the value they had built up on their website and had to start again. In addition the overall quality score that Google allocates to the site suffers which additionally brings down the site. SEO-optimizers can support discovering where there are problems in this area and help to fix the redirect issues.
Here you can see the flow of the redirect from the innitial querie to the server and back to the user.
If there is a choice you should use a 301 over a 302 redirect because on a 302 the rankpage is not flowed through whereas on a 301 there is only a limited loss. Many companies forget to make the redirects altogether and of course there is then a serious loss of pagerank. What is worse is that the customers are treated to the dreaded 404 error. What additionally can happen is that the quality score of the site is reduced because of the number of bad links that are present on the site as a result of this. You need to use a systematic solution to track down where on your site these errors are present and regularly eliminate these types of errors.