With more than one billion users, WhatsApp Messenger is the most popular messaging application in the world.

At some point your child may join the one-sixth of the world’s population who already use it to chat to friends and family.

If you haven’t used WhatsApp yourself, it’s important you know how it works and what it does, in order to keep your kids safe.

How WhatsApp Messenger works

WhatsApp allows your child to send a message to anyone they’ve added to their WhatsApp contacts. Both the sender and receiver need a WhatsApp account in order to use the service.

The free app is available for Android devices, iPhones and iPads, BlackBerry handsets, Windows Phone devices or Nokia phones.

When your child downloads the app, it goes through the contacts stored in their phone and lets them ‘add’ people who also have the app so they can send messages to each other.

One of the reasons WhatsApp is so popular is that it sends messages over the internet using wi-fi or data, instead of using your phone’s text message or pay-as-you-go-allowance.  That means it’s much cheaper than text messaging, and even free if you’re connected to wi-fi. The service used to charge members a small annual fee, but it got rid of it at the start of this year.

Phone with WhatsApp app being installed

You can use WhatsApp to send photos, videos and web links. Another advantage over text messaging is that you can message people in groups, so the same message is delivered to multiple people at the same time, and at no extra fee. You can name the groups too, so you can have one for ‘School friends’ or ‘Family’.

When a message is sent, WhatsApp sends a ‘read receipt’ to the sender so they can can see if the message has been delivered and whether the person you are sending it too has watched the video or looked at the photo you attached.

What the symbols next to the messages mean:

  • Grey tick: Message has been sent
  • Two grey ticks: Message has been delivered
  • Two blue ticks: Message has been read

Recently, WhatsApp enabled end-to-end encryption, meaning that every message can only be read by the sender, the recipient, and anyone else in the group if it’s a group message. It basically makes the service more secure from hackers.

You can also make phone calls through WhatsApp. Again, it uses the internet instead of your mobile’s data connection, so it can work out much cheaper than making a normal phone call if you are on pay as you go and allowing you to save minutes from your allowance.

Connecting with people on WhatsApp

Once your child opens WhatsApp on their phone, they can go to the Contacts section and add people.

They can also create Groups which they invite people to join, and be invited themselves.

By default, WhatsApp shows people the last time your child used their WhatsApp account and whether your child is online right now.

They can also set a status message to let people know where they are and what they’re up to.

[Related story: Facebook - What parent's need to know about the social network]

Child staring at blue phone

Issues you should watch out for

Stranger danger: The main hazard for your child is being contacted by someone they don’t know. But because WhatsApp only lets you converse with people in your phone’s contact list (or whose phone number you already have), this is much less of a danger than on social networks.

Location sharing: If this option is switched on, any images and videos your child shares will include a map showing the location where they were taken. This could reveal where you live and potentially put your child at risk.

Bullying: As with any method of communication, your child is at risk of being bullied, being pressured into sending personal photos and of being exposed to explicit images or photo themselves.

Read more in our guide Staying safe on social media: Advice for parents.

Tips to stay safe on WhatsApp

1. Stop strangers seeing your child’s status: Select Settings - Account, and then Privacy.

Under Status, change it from Everyone (the default setting) to My Contacts. That way, only people they know and trust will be able to see when they last used WhatsApp. Change Profile Photo and Last Seen to My Contacts too.

MyZone app

2. Turn off location tagging: If switched on, any images and videos your child shares through WhatsApp will show where they were taken on a map, potentially alerting dangerous people to their whereabouts. To switch it off, you’ll have to go into the phone’s main settings.

3. Delete, block or report unknown or nuisance users: If your child starts receiving unwanted or harassing messages, they should block them which means they won’t be able to contact your child.

  • iPhone: Settings – Account – Privacy – Blocked. Click ‘Add New’ and select a contact.
  • Android: Menu – Settings – Account – Privacy – Blocked Contacts. Tap ‘Add blocked contacts’ and select a contact.

You can also report abuse, WhatsApp can ban accounts it believes violate its terms, discover how to do this here.

4. Report spam: Spam messages trying to extort money can be sent via WhatsApp, just as they can via email. Reporting and blocking said messages will keep your child – and others – safe. When your child receives a message from an unknown number they will be given the option to report it as spam.

5. Talk to your child: Make sure your child knows they can talk to you if they encounter any problems, such as bullying and abuse. Talk to them about the consequences of sharing personal photos and videos, explain that once a photograph has been sent, it can easily be shared, so they need to think carefully.

For a comprehensive and easy-to-use resource of the most up-to-date information for keeping your child safe online, check out Internet Matters.