Beacons, not bacons. iBeacon is Apple’s version of the Bluetooth-based beacon concept, which allows Bluetooth devices to broadcast or receive tiny and static pieces of data within short distances. In simplistic words, it consists of two parts: a broadcaster (beacon device) and a receiver (smartphone app). The broadcaster is always advertising “I am here, and my ID is…”, while the receiver detects these Bluetooth radio packets and does whatever it needs to do based on how close or far it is from them.
Think of beacons as "buttons or links to the physical world around you". In the same way that web pages rely on buttons as a primary way of user interaction, beacons are used by apps to trigger events and call actions, allowing users to interact with digital or physical things, such as door locks, discounts, automation systems or simple notifications.
From a technical point of view, you can think of iBeacons as small digital lighthouses, just like those used to indicate where a port of shoreline is. Normally, the observer/receiver is an iOS app, while the broadcaster/transmitter can be a battery-powered sensor, an USB Bluetooth dongle, an Arduino kit, a Mac computer or an iOS device. The broadcaster side only sends data. The standard beacon advertisement consists of an UUID, a major and a minor value only. For example:
UUID: B9407F30-F5F8-466E-AFF9-25556B57FE6D
Major ID: 1
Minor ID: 2
The broadcaster (iBeacon) doesn't do anything else besides sending this piece of information every fraction of a second or so. The UUID is an unique identifier. For example, if Starbucks decides to deploy beacon sensors inside its store and make an app that can tell the user once they arrive at a specific store, they would define a UUID that is unique to their app and the beacons inside their stores. Inside the stores, they would place beacon devices and configure each of them to use a different “minor” value. For example, at the store A, they would place all beacon devices broadcasting the Starbucks UUID, major value 1, minor 1 near the door, minor 2 near the mugs display and minor value 3 near the cashier. At store B, they would use the same UUID, but major 2 and minor values according to the location inside the store.
With the information broadcasted by each beacon, the app can detect them and tell how close (or far) the phone is from each of them and then perform actions, display alerts to the user, offer discounts, turn lights on and off, open doors and so on.
Tell me some applications that can de deployed using beacons 
Beacon technology empowers contextualisation based on proximity or location by connecting the physical and digital worlds. With that in mind, see the examples below.
With players like Facebook and WhatsApp offering proximity-based campaigns through their iOS and Android platforms, businesses now have the option of combining social campaigns that physically drive clients to your door using proprietary apps that enable a deeper engagement and shopping experience that can trigger physical events, such as a blinking window display as the customer walks by.
Restaurants have shown us how useful mobile technologies are. Enabled with touch devices, waiters don’t have to rush to the kitchen in order to dispatch orders. In other cases, clients can make orders directly on tablets available at the table. Before iBeacon or NFC technology were around, such apps required the waiter to select a table number every time he/she takes an order. With iBeacons, the app automatically knows which table the waiter is at. It can display the client name (eventually with the client's dinning history/preferences) and automatically associate orders with tables without requiring waiters to manually select a table number.
Business owners can digest analytics data showing which tables (serving which clients) employees stayed more time/compared to client’s satisfaction, and it is even possible to understand and analyze employees' most common paths, least visited/shadow areas and improve efficiency. The same concept can be adapted to a myriad of business kinds: from logistics to hotels and hospitals.
The iBeacon platform offers a wide range or applications that can be applied on an educational context. From simple games that require students to move around, explore and find things to more scientific or technical experiments in the classroom, iBeacon is a great tool to stimulate young minds and drive curiosity towards subjects like geography, context, automation, logic and technology. A great source of examples and experience in how iBeacons can be applied in classrooms is Jonathan Nalder's JNXYZ/Beacons for Education website:
http://www.jnxyztraining.net/beaconsforeducation/
Imagine a Zoo mobile app, which visitors open once they get into the park. When they are close to selected attractions, the app fires a notification/image/video with information of what is being looked at. It can tell visitors: “Feed the monkey some peanuts and watch your arm disappear in a second”.
You've probably seen sushi joints that use conveyor belts to move sushi in front of you. Now, imagine if each of those plates have a small sensor sticked under them. With the restaurant's app opened, hungry customers can see detailed information about what's in front of them, including price, nutrition information, ingredients, origin of the fish and much more. By clicking a 'I got it' button, patrons can also keep track of their current bill without worrying about dish color codes normally used in conveyor belts joints.
All kinds of automation, be it home, commercial or industrial, are directly related to what beacons can offer. From your garage door that opens once your car stops by (without pressing any button) to lights that go on and off as you need them to be. Automated Home
http://www.automatedhome.co.uk is a great source of home automation-related news and information since 1996.
NFC technology does not offer the range of possibilities that Bluetooth does and iBeacons can be used to do something very similar to what NFC does. When adjusted to be ranged within very short distances, iBeacons can be deployed to allow communication between stationary beacons and loyalty program apps. In a more advanced scenario, both the app and the stationary sensor can perform passive (listener) and active (broadcaster) actions, allowing short-range, two-way communication between the app and the iBeacon sensor.
Many airports have already implemented traveller location services that guide and facilitate users locomotion through areas that they’re not familiar with. Normally used in conjunction with airport-specific apps, these services improve user experience, drive sales and help the management understand traveller’s behaviour in order to optimize signage systems and the space as a whole.
Bluetooth Low Energy? Bluetooth Smart? BLE?
Bluetooth Low Energy (BLE) is a new Bluetooth “flavor” offered within the Bluetooth 4.0 standard. For a device (be it an iPhone or desktop computer) to be able to enjoy this new Bluetooth flavor, it needs to be equipped with a more recent Bluetooth chip that is compatible with the 4.0 version of the Bluetooth standard.
Originally, Bluetooth Low Energy was invented by Nokia back in 2006 under the name of “Wibree”. Before Wibree got popular and became available to the masses, Nokia decided to transfer its low power technology to BSIG (Bluetooth Special Interest Group), which controls and standardizes the Bluetooth technology. After being incorporated by the BSIG, the technology was renamed to “Bluetooth Smart”, which is the commercial name of the “flavor” and it is the same as Bluetooth Low Energy, which is the technical name. Bluetooth Smart (or BLE) is only compatible and available on devices that are compatible with the 4.0 version of the Bluetooth Standard.
As the name says, Bluetooth Low Energy is a Bluetooth mode that uses low energy, which is normally used to connect to low data rate devices, such as cardio monitors, temperature monitors, smart watches and so on, but it doesn’t mean that every time you connect to a device via Bluetooth you’re necessarily using BLE. A wireless Bluetooth speaker for example will not use Bluetooth Smart/Low Energy to receive data stream from your computer or smartphone. Also, every time you connect to a BLE device, such as a wearable sensor, it doesn’t mean that you’re necessarily using BLE.
The major difference between the common Bluetooth protocol and BLE is that minimum energy is required for two devices to broadcast or detect BLE packets. Because low energy is the focus, the kind of data/information sent by these devices is also minimum, slim and very slow. That being said, a BLE device is not supposed to transfer audio, video or support any kind of application that requires high bandwidth or large amounts of data.
Ok, but what is a beacon then?
Non-technical people will imagine beacons as a small battery-powered device sticked onto a wall or place. Technical people will say it's a small Bluetooth Low Energy (BLE) device that broadcasts a small amount of data every second or so. At a hardware level, beacons are BLE devices broadcasting data using Apple's “iBeacon” protocol. At software level, beacons are messages sent by broadcasting devices that are detected and processed by receiver devices like a mobile app running on iOS. These data are considered beacons as well, depending on how you name things.
Did Apple invent beacons?
Apple's iOS was the first platform to bring the technology to the masses. Technically speaking, Apple extended its iOS CLLocation class, which previously supported only GPS/Geolocation, to support beacons as well. The underlying technology (BLE) was created by Nokia and the concept of “beacons” is universal to all hardware compatible with Bluetooth Smart/BLE that is available under the Bluetooth 4.0 specification. The iBeacon name and protocol are trademarked by Apple.
Even though Apple developers now have beacons and geo location under the same "umbrella", there is a very essential difference between them: A beacon is not a physical location; it is something that can be placed anywhere and have its location changed at anytime, while GPS locations are always there and forever fixed. GPS locations also do not have major and minor values, and they are public to anyone. On the other hand, iBeacons carry an unique identifier. If the listener does not know this identification, it will never know it is there.
How can I "send" beacons?
All you need is a beacon device, a computer or iOS device broadcasting beacons (UUID, a major and a minor value). In a real life scenario or in stores for example, small devices are normally used. Developers, sometimes, may use computers to act as beacons in order to test and debug their apps.
How precise are beacons?
Aside the unique identifier, major and minor values that are always advertised without errors, the detection isn't always highly precise. The measured distance between the broadcasting beacon and the receiver/app can be unstable or imprecise depending on an array of factors, such as interference in the same radio wave spectrum, obstacles, sensor broadcast settings and so on. Precision strongly depends on the broadcasting rate and power that your beacons are operating and how fast your app is ranging your beacons. Apple, for example, limits the scanning rate to 1 per second when apps are open. When apps aren't running, the scanning cycle becomes totally up to iOS background restrictions. Even if your beacons are configured to broadcast at faster rates (resulting in lower sensor battery life), your iOS app will not be able to scan them at a rate that is higher than 1 second.
If beacons don’t provide precise location information, what’s the point?
It's all about context. The idea is to have beacons placed far from each other and have them properly calibrated. iBeacon devices can have its broadcast power adjusted to levels that allow your app or receiver device to know more precisely which beacon is closer or further. If you have two beacon transmitters placed side by side in a small room and working at full broadcast power, only magic will help your app to know which one is the closest or which one is the furthest - imagine a room with a few people talking. If all of them talk very loudly, you won’t be able to listen to what each of them are saying, but if each person whisper, you’ll be able to listen to each one as you get close to them. Does it make sense?
So beacons only send “I am here” messages?
Not really. It depends on how these devices are made and what they offer from a hardware point of view. Cheaper devices only broadcast the basic iBeacon protocol, while others may offer additional features that can be accessed by BLE or even traditional Bluetooth pairing. Features can range from temperature sensing, motion control, sound or light activation… It all depends on what is in the hardware. An iBeacon device is a Bluetooth LE device above anything else, but its hardware may be restricted to offer only iBeacon protocol broadcasting or its hardware may not have configurable settings, but most beacon devices, even the cheapest ones, allow you to connect to them and change some of their basic configuration, such as UUID, major and minor ID values.
Can I use beacons for indoor location? Estimote has an interesting and robust indoor location solution based on their easy-to-use API. It requires you to have at least 3 Estimote iBeacons and Swift or Objective-C knowledge.
Which smartphones and tablets support it?
Theoretically, any iOS device compatible with Bluetooth version 4.0 (which incorporates Bluetooth Smart/BLE) supports the technology necessary to detect iBeacons.
What about NFC?
NFC tags are passive, while iBeacons are active battery-powered transmitters. NFC can't be used in applications that measure distance between the broadcaster and the ranging device. NFC requires a (cheap) antenna that is not available in all mobile devices. Think as NFC as an “ON/OFF” thing, while beacons offer the distance factor, besides an infinity of possibilities around configurable and customisable broadcast packets.
NFC only works upon very close contact of two devices, while iBeacons have a range of 30 meters or more depending on the case. On the other hand, NFC does not require power/battery on the antenna side (tag), which makes the technology ideal for applications such as smart cards. In the NFC universe, only the reader needs to be powered in order to read the information stored in the tag. In the BLE universe where iBeacon belongs, both the reader and the tag are powered.
What about GPS?
GPS and iBeacon technology complement each other and target different necessities. GPS is widely adopted in applications that require outdoor positioning information without a high degree of precision, such as sports tracking apps or services like Apple’s “Find My iPhone”.
Beacons, on the other hand, don't rely on GPS or Wi-Fi, and they can also be used indoors (where GPS can’t be used with acceptable level of accuracy), providing a much higher level of accuracy in proximity-based applications. Beacons, like GPS, can also be utilised to inform user location within multiple beacons with a higher degree of precision if compared to GPS, but just like continuous GPS positioning, BLE-based positioning techniques can be battery intensive, and in most cases, they require the app to be running and completely open on the device’s screen.
That said, iBeacon technology was primarily created to provide proximity-based or contextual data to iOS apps, where simple and single notifications are dispatched to the app once the user gets close to a venue or object.
