A digital key is something that can grant access to, and or locks/unlocks, and or secures something that is digital. For example a digital key unlocks a digital lock.
But a digital key is not always related to digital locks. For example the term 'digital keys' has often been used in banking with PIN's, and with online passwords - so a digital key does not always have to be a physical thing. Nowadays the term 'digital keys' is increasingly being used in context with digital locks, electronic locks and keyless entry in the access control industry.
Just as a metal key gives access to/secures a traditional metal key cylinder lock (a.k.a an analogue lock) a digital key gives access to/secures digital locks (a.k.a electronic locks). Or put simply if its not a metal key, but it does everything a metal key does, then it's most likely a digital key.
Another way to think of it is like this - if the device has a circuit board (a.k.a PCB) in it, its most likely digital and so it will need something digital to operate and control it. A digital key operates and controls a digital lock which has a circuit board inside it.
A digital key can come in many forms, shapes and sizes, with many different names and technologies used. For example, a common device that can be used as a digital key is your mobile phone. Apple, with its iPhone, and a number of car makers such as BMW and Honda, have announced that they will be using Digital Keys in iPhones to lock and unlock cars in the future e.g see article here about BMW digital key on their website.
Over the last few years many hotels have been adopting digital keys too. Sometimes hotels name their digital keys 'mobile keys' or 'smart keys', or 'open keys', or 'keyless access' or 'app unlock'. These all do the same thing, and that is they provide guest's access to their rooms without a metal key. Of course hotels, for a long time now, have also been using keycards (a.k.a swipe cards, or smart cards, or mag-stripe cards) as room keys too. So keycards are another example of a digital key, although its not common to see them labelled as a 'digital key'.
Where as the digital key is used almost primarily with a digital device with a PCB inside, a digital key doesn't necessarily have a PCB inside. The most common example of a digital key that does not have a PCB device in it, is the aforementioned PIN (e.g used in banking or online passwords).
A digital key can also be, but not limited to, your car key fob; a token such as NFC card (e.g your credit card); or your fingerprint (fingerprint unlock on phones, and electronic locks). A digital key can even be your face - facial recognition technology is being used in some smartphones to unlock them and give you access to your phone. Of course all these things have something in common and that is they unlock/lock something that is digital.
It might seem a little strange to say that your finger or face is a digital key, but certain technologies such as biometric authentication enables this. Other common technologies used with digital keys include Wi-Fi, Bluetooth, Near Field Communications (NFC), Radio Frequency ID (RFID) Zigbee, Z-Wave, Ultra Wide Band, and Wide Area Network technology that exist on mobile networks such as 5G IoT.
To learn more about digital keys for digital locks, visit www.digitalkeys.io