Bluetooth is one of the great survivors and adaptors of the mobile world, defying predictions of its looming irrelevance every few years by evolving new skills and remaining a key part of the tech spec of today's newest and most edge-cutting smartphones.
At its most basic level, Bluetooth is a wireless method of connecting gadgets, a bit like today's ubiquitous Wi-Fi protocol, only without the need for a central router to manage the connections. It's more personal, like a digital handshake.
Phones with Bluetooth in them can connect directly to other mobiles within a few yards of each other, making it an ideal way to share small pockets of information between phones, like sending contact details and sharing MP3s with friends.
Bluetooth is also a feature of many laptops, plus it's universal -- a laptop can see and share data with a phone, a game controller can link to your tablet and much more. You pair a couple of devices through the options (so complete strangers can't send you random files), then they're linked and you can transfer your stuff through your phone's usual sharing system.
This simplicity is why it's still around. It's the glue that holds the tech world together. Here's how it works.
Bluetooth specs
Managed by the Bluetooth Special Interest Group – a non-profit collective of several major mobile tech firms – the technology keeps evolving, with the latest 4.0 spec using less power than ever and opening up yet more options for linking things to other things without having to find and untangle the relevant cables.
The Bluetooth you have on your flash new smartphone today is likely to be v4.0 of the protocol. Each few years Bluetooth refreshes its spec, building a new set of tools to take into account modern hardware developments while also unifying the standard to ensure all devices can chat with each other.
Earlier revisions saw it add support for streaming audio as well as file transfers, opening up the horrifying world of the hands-free Bluetooth headset, before its audio capabilities were later updated with higher bandwidth rates thanks to the Advanced Audio Distribution protocol that also allowed the transfer of two-channel stereo audio at a decent bitrate.
Enabling Bluetooth
The precise technicalities of activating Bluetooth will vary depending on your variety of mobile phone (or laptop, controller, tablet, etc), but there's only one real approach to doing so. You switch it on and make sure your device is "visible" and broadcasting its availability. That's the important first bit. Second, and a bit more complex, is pairing your device with another so they have a trusted and secure two-way link.
This usually involves one device sending a request to another phone or laptop for permission to access and share files. This is an important part of the Bluetooth chain, as it means you control who can and can't access your phone.
Once that initial permission request has been okayed, you should be free to initiate the sending and sharing of content via the little wireless link. Most modern phones will let you specify a visibility timeout as well, meaning there will only be a small window of time during which your phone is broadcasting its availability on the Bluetooth channels. Another nice little security feature.
Bluetooth security
There's been the odd low-level concern over the years, but Bluetooth's key pairing mechanism and authorisation system means that you're pretty much bulletproof from outside attack. The only way someone can "see" your phone or laptop over Bluetooth is if you make it available, then allow them access. And if you do all of that, you probably know them, and are sitting next to them, and don't mind letting them ping you photos, MP3s and contact details through the air.
