OAuth is the Open standard for Authentication. OAuth makes it easy to log in to one site using the credentials supplied by one of the other social networking sites. It uses access tokens to give server authorization to third party clients with the permission of the end user.

But beware.

Giving authority to a site such as Pinterest the ability to use your Facebook, Google or Twitter login gives Pinterest the ability to data mine all of the information you have given to the other site. Pinterest does not need to collect any information from you. it already has this from Facebook or Twitter.

Pinterest will then suggest connections for you to follow on Pinterest based on your Facebook friends and the pages you follow.

Go through your Facebook settings — and your Twitter settings and revoke access to sites and apps you no longer use.

Twitter gathers data from the interactions you have on Twitter, the information you provide when you registered for a Twitter account and its relationships with its ad partners.

When you follow someone, send a tweet, search or interact with users and tweets, the data is used to tailor Twitter Ads. If you search for a specific term, promoted content related to that topic could appear in your feed. Your profile information, location or mobile device location  could be used to show you local ads.

Twitter also receives information from its ad partners. This could be browser cookies and email hashes. This means if you have signed up for email newsletters you might see an ad from the brand where you signed up.

If you do not like this feature you can turn it off by using the Do Not Track Feature in your browser. Alternatively uncheck the box that says “Tailor ads based on information shared by ad partners” in your Twitter security settings.

Facebook is looking at your browsing history and apps that you use frequently. It uses this to deliver targeted ads to your Facebook page.

You will be able to see why you see a specific ad from its new preferences tool. You can add and remove interests to refine which ads you see.

In the US, you can opt out from receiving interest based advertising from participating companies such as Facebook. You can also use DuckDuckGo as your search engine of choice.  

LinkedIn collects a huge amount of data from you, your connections and your browsing information. It also collects information from hashed email exchanges so that it knows which connections you might know and which groups you might want to join. It shares information with its ad partners to deliver targeted ads and information to you.

To turn this information off go to your LinkedIn settings. Select the Groups, Companies and Applications tab and uncheck the check box for data sharing with third-party applications.

Pinterest collects data that you have voluntarily submitted such as your name, profile profile photo, pins, comments, likes and your email address. It also collects other information such as location data from a mobile device.

using OAuth to log on to Pinterest from sites such as Facebook, Google or Twitter gives Pinterest the right to extract data about your friends and contacts.This information depends on the settings you have enabled in Twitter or Facebook.

Pinterest also collects data to log such as web page or app visits to Pinterest and the Like button. This data includes standard information such as your IP address and the type of browser you are using.

Pinterest also collects browser cookies and the device you are using to access Pinterest. It then uses this data to deliver customised content such as suggested boards and ads of interest.

To choose what information Pinterest uses, go to your account settings and update the personalisation preferences. Change the radio button to show you related pins based on your activity on Pinterest. You can also change the visibility of your profile to search engines.

Also check whether you have enabled OAuth from Facebook, Twitter or Google.

Google+, as part of the Google software offering, gathers information about you through web and image searches, searches for blogs and news articles. It also watches which websites you have visited through web analytics and the search results you click.

Many users of Google+ have a Gmail account. Google reads every email sent and received to Gmail. Google also has direct access to every tweet sent and received. If you use Google docs either at work or for personal use, then Google will collect data about usage.

Google also monitors your email contact list and works out the connections between your contacts to show you suggestions of people you might like to add to your Google+ circles.

If you have completed your public profile, then Google also uses this information. If you have clicked on an ad then Google knows which keywords are popular and which ads attract the most clicks. Google even knows which parts of the world you are most interested in if you use Google Earth. All of this data feeds back into its massive data bank.

If you are unhappy about the information that Google is collecting you can configure privacy settings in your Google dashboard. You can check your Gmail stats, have a look at your credit card information, and your web browsing and search queries by date.

There is no way to remove all of your search history with one click. I had to delete each individual search query I had made — right back to 2008. 

Another way to stop Google using your data is to stop using any of its products.