The issue of duplicate content is a multifaceted one. This is particularly true when it runs headlong into optimizing your website from a Google SEO perspective.

What is duplicate content? Simply put, any content appearing in more than one place on the internet is going to fall under the heading. This extends to not only different websites, but also to websites which feature duplicate content across several of their pages.

Does Duplicate Content Harm My SEO?

Duplicate content is not inherently wrong, but it can very easily cause problems for your website’s ranking on search engine giants like Google. The issue of Google duplicate content can come down to Google becoming confused with which version of said content is original, and therefore an important component for ranking.

If confronted with several versions of duplicate content, a search engine like Google will simply show one of them. This in turn is going to dilute the overall visibility of every website using the content. Inbound links, a crucial ranking factor, are now being divided up among a range of different sites. In other words, visibility drops on search engines.

What Are The Main Causes Of Duplicate Content?

Duplicate content can actually come from a variety of different places. Here are the most common causes for duplicate content that you should keep an eye out for:

URLs: This can mean having multiple versions of the same content across several different URLs.
Session ID: These IDs allow your visitors to come to the site, use a shopping cart, and similar activities. However, since search engines generally don’t store cookies, some systems will return to using the same session ID for every internal link.
URL Parameters: Some URL parameters are not capable of changing the content of a page. This can create a frustrating duplicate content SEO problem for Google.

There are a few others you should keep in mind. This can include order of parameters, comment paginations, and even whether or not your content is available in both a WWW version and non-WWW version.

Up to a point, it can be almost impossible to completely eradicate duplicate content in every possible form. To that end, it can be helpful to understand at what point you become open to the likelihood of being penalized by Google for having duplicate content.

What Are The Different Forms Of Duplicate Content?

Before we continue on, let’s briefly go over some of the most common forms of duplicate content. This will help you to better understand the Google penalty for duplicate content:

Boilerplate: Content appearing in different website pages
Copied/Scraped: Copied content is definitely going to show up. Same with content scraped from other sites.
Curation: Stats from other sources are fine. Just put the best content around it!
Syndication: Third-party websites using snippets of content from major sources.

Do I Need To Worry About Being Penalized For Duplicate Content?

Unless your website’s content is being deliberately duplicated to manipulate search engine results, you don’t really need to worry. Duplicate content can be problematic, but Google isn’t going to refer to it as spam.

Spam is what you don’t want associated with your website.

Having duplicate content in of itself is not going to lead to being penalized by Google. On the other hand, if you have millions of such webpages on your site, you are indeed putting up some very big red flags for Google or any other search engine.

At the end of the day, focus on high-quality content with an emphasis on originality. As long as you aren’t copying content on purpose, you’re going to be able to avoid problems more often than not.

What you don’t want to do is

Take content from an existing website, making only the most minimal changes to the material, or adding a few different keywords.
Repeating content that can already be found on your website. This is not really a problem up to a reasonable point (you’re bound to repeat a product, service, or something similar across different pages)

The Best Tools For Finding Duplicate Content

Here are some of the most useful tools for finding duplicate content:
Siteliner: A great SEO tool that allows you to analyze the content on your website for duplicates. The free version will check 250 pages for you every thirty days.
Copyscape: A great free tool that lets you search for duplicate content across the internet by pasting your own text in.
DupliChecker: A simple tool that checks through any piece of given content.
Grammarly: Checks not only duplicate content, but also your spelling and grammar!