To put it in simple terms, Near Field Communication, or NFC allows for two devices, often a mobile phone and something else, to communicate and exchange data when near each other. This type of communication is often used to make purchases with a simple "tap" of a smart phone or to gain access to an area when used like a digital key or pass. Near Field Communication can transfer other data as well, like contact information, photos, song or video media, applications or link bluetooth devices. Although similar to bluetooth technology, NFC consumes less power and is considered more secure than its bluetooth brother.
The first concern on anyone's mind is safety. Identity and credit card theft are a scary thought. Couldn't credit card data sent via Near Field Communication be easily hijacked or fake? The fact that nothing is being swiped or physically handed over attributes to this fear. This same paranoia is seen when shopping online, something that seems common place now. In previous years most consumers didn't feel safe just "giving out" their credit card information online where it seemed like anyone could steal and abuse it. To start, simply "stealing" sensitive data transferred using NFC would be physically difficult. The maximum distance for this type of communication is about twenty centimeters meaning anyone physically looking to hijack your data would have to be very obvious about doing so. That aside, any encryption used by companies such as credit companies is transmitted over the NFC signal. For those who still don't feel safe, Near Field Communication can be simply turned off when it's not being used.
Current use of Near Field Communication is spotty at best. Many companies have started, or plan to start using the technology, but very few have fully embraced it. Regardless, there's a lot of potential and a lot of plans in the works for the future. The biggest proponent of NFC is the credit card companies. Credit cards in place of cash has already shown to increase impulse buying for the common consumer, but what if you don't even need to take your credit card out of your wallet? Instead, simply waving or tapping a smart phone to a receiver can make purchases, treating your smart phone like a digital wallet. The field of transportation can benefit from this technology as well. Companies are always looking for new ways to streamline transportation, whether it's checking in, boarding a plane or train or paying for tickets. Travel can always be something of a hassle, so any big of convenience of travel company can add can be a big leg up on the competition. In some big cities travelers can already find themselves checking in or boarding instantly by tapping their smart phone to an NFC receiver. This trend began with a pilot program in Germany which let pilots, who are always on the run, check in just by tapping their phones.
Here lies the barrier or Near Field Communication. Not just any company can start employing NFC for their transactions or ticketing. The technology and the hardware behind it has been available for a long time, but it's not as easy as printing out a barcode like for other similar types of digital data transfer. Instead, a computer chip needs to be purchased and embedded for smart phones to connect to. Aside from that, a limited amount of smart phone models are even compatible. With the potential for this technology clear though, especially on the commercial side of things, companies are not willing to let its slightly less accessible nature get in the way. Many big name companies like PayPal, Microsoft and even Coca-Cola have discussed finding ways to really promote NFC in the future, leading mobile phones like Apple and Android to commit to creating future phones that are NFC ready. Even if Near Field Communication isn't common place yet, it seems like leading businesses are determined to make it a thing of the near future.
Near Field Communication on Wikipedia
Sure, Wikipedia provides a lot of information on how NFC works, but the most interesting part is the lists of companies and countries which are embracing NFC and how they're doing it.
A non-profit organization that works towards education the world about Near Field Communication and promoting its potential uses.
NFC vs Ordinary RFID in Mobile Phones
Near Field Communication exists largely in part to its RFID predecessor. Learn how the two compare.
NFC Technology: 6 Ways It Could Change Our Lives
A good, brief overview for how NFC can affect the average person, and why you should be interested in it.
Everything You Need to Know About Near Field Communication
For those looking for more than just a brief overview, Popular Science goes in-depth on the tech behind NFC.