It's a fair bet that most of you reading this use Facebook.

It's used by billions of users worldwide, and many people can't go anywhere without sharing the details of their trip and posting photos of their kids in far-away places.

As such, it's an ideal way to keep in touch with friends and family, so much so that it's become almost indispensable for many, and due to the way apps work on our mobile phones, it's with us all the time.

Always logged in

One of the big benefits of Facebook is that nearly everyone who uses it is always logged in to the site. This means you can instantly tap out an update or upload a photo, it's extremely convenient.

It also means that same data can be used by other websites.

Have you noticed that some sites will allow you to “log in with Facebook”?

Many of us do this because it's simple and extremely convenient. In today's busy world, convenience and simplicity are just what many of us are looking for, but unfortunately, some companies took advantage of this.

For example, you may have taken part in a survey.

There are many of these popping up on our feeds. They have enticing titles like “Nobody can answer all ten questions!” which just lure you into clicking, logging in to some new website and answering what turn out to be really easy questions.

You then post your results because, as told by the website, you're in the top 1% of people in the UK.

Clever you!

It turns out that they've just grabbed a whole load of data off you.

How they get the data

When you use your Facebook account to sign in to a website or app, you'll be asked, quite clearly, whether the app is allowed to access your profile.

It sounds innocent enough, and obviously, you can back out at that time. But, many people continue because they want to find out how clever they are.

So they grant access.

Sometimes, it will then ask if it can have access to your friend's list. The excuse here was so they can better tailor adverts and promotions, but really, they want their data, too.

The sinister thing here was that unscrupulous apps and websites could get hold of data about people who hadn't specifically given their permission. And that's not right.

Facebook closed this loophole some time ago, but it doesn't stop companies using other methods to get hold of it, for example, simply encouraging you to share the results of their quiz.

So what do they know?

It's hard to tell accurately what companies know about you, but there is some data that's really easy to extract.

For example, your phone has a GPS system, it knows exactly where you are at all times, and you'll notice that when you post something from your favourite holiday resort, Facebook knows.

This can be very useful, for example, you might find friends close by (or know that you have to avoid them!), but it also means you can get localised information just for you.

You'll notice your feed changes to include adverts for local bars and restaurants or theme parks.

It's all very clever.

But it can also mean you're giving a little too much away.

For example, if you're skiing in France, it means your house is empty.

Do you really want to broadcast that to the world?

How to protect yourself in three simple steps

1) Just delete Facebook

To be honest, this will be like suffering cold turkey for many people. Doing without Facebook would seem like a sacrifice too far, and many feel lost without it. But, it's the only way to be totally sure your data isn't going to be used.

Facebook assures us that when you delete your account, all of your data will be gone in 90 days. How much we can trust them, we just don't know.

To do it, click on the little down arrow next to the question mark in your Facebook account (it's best to do this from a computer rather than mobile phone) and click on “Settings.”

On this page you'll notice that you have an option of downloading a copy of your Facebook data (1).

If you click on this, you'll be able to download all your messages, pictures and anything else you've ever shared.

Looking at this can be pretty eye-opening.

When you're done downloading, or you've decided you just want to let go, then go to the following link:

https://www.facebook.com/help/delete_account

Easy as that!

Well, not quite.

In fact, if you log in within the next couple of days, your deletion will be cancelled, they don't want to let you go that easily!

2) Turn the privacy up a bit

OK, maybe deletion is not for you, but you're a bit unsure about telling everyone that you're not at home.

The best way to do this is to make sure your posts only go to friends.

Go to settings again, but this time, click on “Privacy”.

The item headlined “Your Activity” is what you want to check.

If it's set to “Public”, then you should consider changing it.

It's easy enough, just click on “Edit” and change it to “Friends.”

3) Think about what you're posting

The biggest problem with posting to Facebook is the information you give away.

If you're constantly updating people about the latest gadgets you have, the best places to holiday and your amazing new car, then you're essentially advertising yourself to everyone, and someone could take advantage.

Also, when you share data, take part in quizzes or fill out a questionnaire, remember that you're being asked for information that will be used in some way – are you happy about that?

Is our data safe?

Hmmm, interesting question!

The simple fact is, we are providing information and useful data all the time.

When we use websites, order online or use an app, there's data that is useful.

It can be used by companies to target us for all kinds of reasons. In some cases to provide us with personalised and useful information, but in others, to influence us.

It's the influencing of the masses that has got people upset recently, and it's this that will be addressed by the various committees and investigations going on, but it's something that, ultimately, we have control over.

We live in a connected world which isn't going to go away.

The best defence is to be careful with what you share and who you share it with.

Be a user of Facebook, and try not to be used.