Facebook knows what you are thinking of buying, here is how

It's not a secret that Facebook collects information about you. All web companies, especially the large ones like Google, Facebook, Twitter etc do. It's for 'research purpose' and to improve the experience. And it is for, as Facebook says, "to show you adverts based on things that we think you care about".

So, how exactly Facebook knows what you want to buy and shows you ads that almost always seem relevant. And how you can manage the information you give to Facebook... to some extent, that is if you don't like to see relevant ads.

In recent times the social media giant has been accused of tracking users even if they have deleted their accounts. Some researchers have suggested that Facebook puts cookies, fragments of software, in users' computers which helps it to track the user even after removing the account. While the practice of sending cookies is not illegal, it is also important that users should know how this works.

This practice of sending cookies is followed by almost all the websites. So when you search on the web for a trip to some hill station, Facebook will start showing you ads for hotel deals. Or if you liked a page of a certain company of smartphones on Facebook, you may find relevant ads on other sites too.

The sharing of user information with advertisers across the web falls under Digital Advertising Alliance. And it's not illegal, if you were thinking on those lines. In certain regions as the US, Canada, Europe, one can opt out of this advertising tool. But in countries like India, this option is not available. However, Facebook allows you to manage what you see in ads or if you don't want it to use your information from websites or apps.

Here is how you can do it:

- Click on 'X' or arrow next to an ad. Press 'Why am I seeing this?'

- Select 'Manage Your Ad Preferences'

- This page will show you a list of preferences based on "information from your profile as well as actions you take on and off Facebook".

- You can remove a preference by clicking on the cross in front of it. Removing a preference won't reduce the number of ads, just that it will not show you ads related to it.

You can also turn off online internet-based ads from Facebook by going to Settings > Ads > Ads based on my use of websites and apps .

By turning it off, in simple words, you have asked Facebook to not use data collected from other websites. So the ads will not be based on what you do outside Facebook. That can be a bane or boon depending on what you want as it will reduce the relevance of the ads.