Sometimes a technology comes along and changes the way we live forever. It often starts quietly. The tech might have to pass through a few iterations before its value becomes clear. The first cars needed three operators, including one to walk in front of the vehicle while waving a red flag. Thomas J. Watson, former chairman of IBM, might not have actually put the total demand for computers at five, but an early model made by his company picked up just 11 preorders. It cost between $12,000 and $18,000 a month to rent.

So some of the technology that you're ignoring today could well turn out to be stuff you can't live without tomorrow. Here are five technologies you need to watch.

1. Digital Currencies

You've probably heard of bitcoin, even if you haven't used it. You might never use it, and Facebook's Libra might never take off, but you will be using some form of digital currency in the future, even if you don't notice. Some of the world's biggest banks are already experimenting with cryptocurrencies. J.P. Morgan, for example, successfully tested its JPM Coin earlier this year. The aim isn't to replace dollars and euros but to create an infrastructure that makes international transfers easier by sending them as digital coins tethered to a fiat currency to keep the price stable. Even if you never own a bitcoin wallet, you could own a digital coin, even if it's just for the minutes it takes to send or receive a transfer.

2. The Blockchain

Digital coins are powered by the blockchain, a kind of digital ledger. Cryptocurrencies like bitcoin keep the contents of their ledgers safe by sharing copies across thousands of different computers that constantly check others. Proprietary coins, like JPM Coin, might use a private blockchain controlled by the company.

But digital currencies aren't the only use for blockchain technology. A ledger that can't be hacked or changed, and whose entries can be used to initiate actions such as releasing stock or issuing a receipt, has uses that range from the supply chain to the sharing economy. Again, you're not going to put a blockchain in the corner of your living room. But you may well come to rely on the blockchain for everything you buy for your living room, to ensure its delivery and lower its price.

3. 5G Networks

The jump from the first generation of mobile phone technology to 2G was huge. The first generation only allowed voice calls, and often dropped them. 2G networks were digital, and introduced not just stable connections but also SMS messaging and conference calls. The leap to 3G enabled multimedia services and streaming, and was a big move too. The upgrade to 4G was more about improving quality than introducing new services. 3G networks let us watch movies on our phones; 4G networks mean that we can now watch them without buffering.

5G networks promise something altogether different, but we won't feel it in our phones. Sure, pages will load faster but they load fast enough now. What 5G networks will do is allow everything we own to be connected. Fridges will be able to download upgrades. Washing machines will be able to alert a technician when they break down. Smart cars will talk to one another, asking for space when changing lanes, and link to traffic lights to ensure a smooth flow through city streets.

Again, you won't really notice the extra speed on your phone. But you will take for granted the extra speed of life around you.

4. Artificial Intelligence

Artificial Intelligence is the big, scary new technology. Minds as smart as Stephen Hawking, Bill Gates, and Elon Musk have all warned against the dangers of creating a digital brain smarter than a human.

But we're doing it anyway.

You can already feel the growth of A.I. in marketing that delivers personalized offers based on the reams of data that tech companies collect about us. You also use A.I. every time you ask Siri to tell you a joke, or give your details to a website chatbot. In the future, A.I. will be used to make smarter decisions about everything from agriculture and aerospace to transport and health care.

Despite the warnings, this one isn't going away.

5. Quantum Computers

We're very much in the early days of quantum computing. In October this year, Google announced that its Sycamore quantum processor performed a task that the world's best supercomputer would require 10,000 years to complete. It finished the job in 200 seconds.

That task, though, was about producing random numbers--difficult but not very useful. Computers whose bits can be both 1 and 0 at the same time still have some way to go, and their value won't be in faster home computers or better video game consoles. It will be in powering the blockchains, the artificial intelligence, and the huge amounts of data that 5G networks will generate.

Together, these technologies will bring a whole new world.