The Cambridge Analytica scandal, and subsequent apology by Facebook chief executive Mark Zuckerberg, have drawn attention to a little-known feature of the social network — downloading everything the social media network knows about you.

Available via a link on the front page of Facebook's settings menu, downloading your data was once known as an easy way to grab all of the photos and videos you have ever posted to Facebook.

But in the wake of reports that Facebook data on 50 million users fell into the wrong hands — and fresh concerns over how much access the social network has to your data and that of your friends and family — understanding what the company knows is more relevant than ever.

How to download your data from Facebook

• Head to the settings page of your Facebook account, or click here, then click 'Download a copy'.
• Click the green Download Archive button
• Enter your password when asked
• Click submit

It took around 25 minutes for our archive to be ready for downloadGearBrain

After these steps, you receive an email from Facebook confirming the request for your data. Then, around 25 minutes later or less (or more), a second email arrives to say your data is ready to download. This morning I did exactly that, and downloaded a 920MB folder of everything Facebook had about me. Here's what I found out:

Clicking on the index.html file opens up a simple way to navigate through the data you have just downloaded, instead of wading through folders of images, messages, video and other data.

A list of everyone you have ever known

First, I headed to the Contact Info tab, which lists — in no particular order — just about everyone I have ever digitally communicated with since I was about 17 years old. In this list there are friends, family members and work colleagues, plus people from school, college and university, and some names I simply don't remember.

To be clear, this is not a list of my Facebook friends. This is a list of everyone in my life whom Facebook knows the name of, along with their phone number and email address if Facebook knows it — which is almost always does — because you wouldn't have a contact in your phone book without these details.

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Many of the phone numbers and email addresses have come from the work email account I used at my former employer, and I would say everyone who ever contacted me on that address is listed here. Most of these email addresses are for work and so can probably be found online if you look hard enough. It is still discomforting to see this huge list and know it came from Facebook.

Other details have come from Facebook itself, such as email addresses of people I once knew and added into my smartphone. One, the mother of an ex-girlfriend, I added to my iPhone a couple of years ago and have since deleted. Facebook, however, has kept it.

Facebook's justification for snooping around like this is the same as its defense this week for recording Android call and text message metadata — to help you connect with people.

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It shouldn't feel weird to see these phone numbers and email addresses. They are not complete strangers and everyone here has communicated with me in some form or another over the last decade or so. But there are people on this list who are no longer in my life — and in some cases no longer alive. Giving Facebook users the ability to rediscover phones numbers of people they had deleted — or people they had been asked to delete, like after a breakup — is clearly a problem.

The social network says "you are always in control of the information you share with Facebook," but how many of the people on this list know I still have their phone number and/or email address?

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'Advertisers with your contact details'

Because advertising is how Facebook earns its money, I went to the 'Ads' tab next and scrolled down to the ominously-titled 'Advertisers with your contact details.'

Here I found a list of 19 companies and websites, most of which I know I've given my details to over the years. The BBC is here, along with Airbnb, Uber, Deliveroo and The Economist. EBay.co.uk is there too, which is fine. But more confusing is why eBay Germany and eBay Canada are also there.

Clicking on the 'Profile' tab shows all the email addresses I have used to log into Facebook, the date (to the exact minute) when I joined, information from my public profile like my gender, location and hometown, my education and workplaces. Facebook also keeps a list of 'previous relationships', based on fellow users you've noted as such on the site. However, I notice that if that person has since deleted their profile, they do not appear here.

Facebook's data collection is prompting some users to consider leavingiStock

The 'Timeline' tab is a complete history of anything ever written on your wall, by you or your friends. For me, this was mostly uninteresting status updates and an annual smattering of birthday wishes. This section is fairly innocent, but serves as a reminder of how, between about 2007 and 2010, we all used to post statuses in the third person, and that subjects which would now be sent in a private message were plastered over each others' walls instead.

The 'Photos' and 'Videos' section are self-explanatory. They don't include anything you are tagged in, but every image you have posted yourself, plus any comments they received.

'Friends' is a list of every friend you have on Facebook, ordered by the date you connected. Below this is a section for friend requests you have received but not acted on, requests you have declined, friends you have removed, and people who follow you but are not your friends.

Every Facebook conversation you have ever had

Next up is the Messages tab, which is a record of every private conversation you have ever had on Facebook. As with the rest of this data haul, it is difficult to navigate and is in no real order. I found it easier to view this data as a list of local files rather than through the html browser; that way, I can order by file size and expect to see my closest friends (those who I communicate with the most) at the top.

Conversations with people you are no longer friends with — and with those who no longer have a Facebook account — are here but their names are replaced with 'Facebook User', so finding specific chat logs is tricky. People you have spoken to, but have never been friends with, are here too but they also appear as 'Facebook User.' It turns out that unfriending someone is not enough to remove your chat history with them from Facebook's server.

The 'Events' tag is where Facebook lists every event you have ever attended, and every event you have been invited to. Even if you didn't interact with the event in any way, it's in this list. I don't really have a problem with this, but it seems strange that this data still exists years after the events — events I didn't attend — took place.

A couple of years ago, this data probably wouldn't make many Facebook users feel uncomfortable. Friends lists and chat logs are made by us, after all. But in the wake of the Cambridge Analytica scandal, and amid the #DeleteFacebook movement, seeing this data could be enough to make at least some of Facebook's two billion members think twice about continuing to use it.

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