When looking to join a wireless network from your smartphone, laptop, or tablet, users are typically presented with a list of names to click on. These names are known as service set identifiers (SSIDs), which can either be the default labels given to the network by the manufacturer or a customised name created by the owner.

Default SSIDs normally follow a distinct pattern unique to the manufacturer. For example, Virgin Media begins its SSIDs with the prefix VM followed by a set of numbers, such as VM-12345. Sky and BT follow a similar pattern. A number of manufacturers also do this with devices they sell to the consumer, such as Netgear.

You may wish to change the SSID from a set of letters and numbers into something more memorable and to distinguish it from similar routers in the neighborhood. This can be done by accessing the web-based admin settings found in nearly all modern routers.

This is also the case if you have many networks in one building – for example, guest Wi-Fi and employee Wi-Fi – that you want to keep separate. Just change the names to make it clear who should use which network.

Key features of an SSID

One common theme you’ll find with an SSID, whether it’s the default set by the ISP or router manufacturer or you’ve changed it, is it features up to 32 case-sensitive letters and numbers. Although you can use up to 32 characters, there’s no lower limit, but it’s recommended you don’t make the SSID so short that it causes confusion (for example “me” or a couple of digits).

SSIDs are normally provided as part of the set-up materials and printed on a sticker attached to the outside of the router, which also includes the password. Alongside the SSID and password should also be the username and password for the router’s administrator console, which grants access to network data and options for configuring settings, including the SSID.

How devices use SSID to connect to the internet

Whenever you setup a connected device for the first time, or when attempting to connect to a new network, you will be asked to configure your access to the internet. You will typically be prompted to scan for available networks in your area and choose the most appropriate for your needs, often a home or business Wi-Fi. These will show as either open and free of any immediate authentication checks (although these can come later through a browser), or locked, symbolized by a padlock symbol. If you wish to connect to a locked network, you will be asked to input a password before your computer attempts to contact the host.

However, this list of available networks will only show those that have been configured to publicly display their SSID or personalized name. To access any hidden networks you will need to input their SSID or name manually, alongside the password if necessary. To prevent a network from displaying on the list of available connections, you will need to choose ‘hidden’ or ‘disable SSID’ in the router’s settings.

Once your device is connected to a network, you can save its details and connect automatically each time you enable Wi-Fi.

SSID security

Although SSID is used by almost every wireless network around the world, it’s considered to be a relatively unsafe way of connecting to the internet, because even if you’ve chosen to hide your SSID so it’s not discoverable by to others, software and apps have been developed to uncover any hidden networks.

Even if such an app or software isn’t employed by people hoping to find hidden networks, some data packets leave traces of the SSID they’re travelling through as you send requests. If these are intercepted, hackers could identify the name of your network if they want to.

Another reason why SSIDs aren’t that useful is that if a lot of your neighbours use the same ISP as you (for example, BT or Virgin Media), their default SSID will probably be very similar to yours and as so few people change from their default network name, it’s quite easy to accidentally try to connect to the wrong one.

And, for example, if one of you doesn’t have security switched on, you may find that smartphones and other devices set up to connect to the strongest network may be using the wrong connection by default. If the network without security doesn’t have large download limits, it could result in a hefty overage bill or throttled speeds.