Having a lot of thin or duplicate content on your website is not going to do you any favours at all in the SERPS (Search Engine Results Pages). Google looks at the content on your website to decide how high or low to place it in the results, and if you have a lot of pages which basically say the same thing, they will class it as duplicate content and you will not rank as high. ‘Thin content’ means pages on your website that do not have much text and do not offer much value to the reader, and Google also downgrade pages like this.
So what can you to improve the quality of your site and address problems with think content and duplicate content?
Identify & Remove Duplicate Content
The first thing to do is log into Google Search Console and take a look at the pages that of your site that Google have indexed.
Remember that Google treat pages with www and without it as two completely different things, so if your site is indexed as http://www.mysite.com and http://mysite.com, that is duplicate content.
They also treat https at http pages as seperate as well.
If you do identify any issues such as this, you need to redirect one version of the website to the other. For example, when the user types in http://mysite.com, they should be redirected to http://www.mysite.com, or vice versa. This redirection can be done by editing the htaccess file, and you can find a full tutorial explaining the process here.
If your site is a blog, make sure the full articles are not displayed on the homepage or on the category pages. Instead you should just have an excerpt with a link for the reader to click to read more. This avoids duplicate content across your pages.
Another useful thing to do is consolidate pages together which have very similar content. For example, if you site is an online store and you have five pages for each product which basically say the same thing, put all of the content on one page and delete the other pages or redirect them.
As well as not having content duplicated across your site, you also need to make sure that your content does not appear anywhere else on the web. There are quite a few tools which you can use to do this, with Copyscape, being one of the most popular.
Identify & Remove/Update Thin Content
As with duplicate content, you want as little think content on your website as possible, so if you find lots of pages that get very little traffic and add no real value to the site, it is a good idea to delete them. The other option is to merge pages together or update each page with new content.
Any pages which have under 200 words could be classed as thin content, and a lot of people will make sure that they have well over 400-500 words on every single page to make sure that they do not get seen as poor quality in the eyes of Google.