For four decades, Las Vegas in early January has been the time and place to find a window into the future.

Or so the organisers of the Consumer Electronics Show, the technology industry's Davos, would have you believe.

The show brings together thousands of companies showing off their latest inventions, from the inspired to the downright ridiculous: last year's "innovations" included a shoe that tells its wearer when they fall over.

This year's show is no different. Some 4,400 companies and almost 200,000 individuals are due to attend CES.

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They include Silicon Valley's giants: Google, Apple and Facebook will all be there, although with different profiles. Google has reserved 18,000 sq ft of exhibit space, while Apple has no official presence, but a handful of individual attendees.

And each year, among the chaos of the convention, pundits and analysts attempt to identify what the show tells us about where we are going: what technologies will capture our lives in the years to come.

The reality is slightly different. Veterans of the tech industry have long rolled their eyes at the jamboree, which has become the source of one disappointment too many.

Ideas that have dominated the show in bygone years, from virtual reality to drones, have not proven to be the consumer hits that their pioneers had hoped for.

Silly ideas are nothing new in the tech industry, of course.

Electronics companies have been showing off internet-connected fridges, an idea that nobody wants, or has asked for, for two decades now.

A lot of this can be forgiven.

Trial and error, or in Silicon Valley parlance, "failing fast", is what tech is all about.

While fridges you can watch Netflix on are a bad idea every year, other ideas, like virtual reality, may simply be before their time.

Few innovations catch on immediately, because when first introduced they are typically underpowered and overpriced. Touchscreens have been around for 35 years but it took until this century for them to achieve critical mass.

Analysts are fond of referring to the "hype cycle", a journey that new technologies must go through before they are taken seriously.

First, they are built up by futurists and wide-eyed early adopters, then as sales fail to match such lofty expectations they are seen as a failure.

Finally, gradual improvements mean they eventually work their way into everyday life, albeit with little fanfare, as they become cheaper and better.

Not every technology makes it through this cycle, but several do.

"Smart home" devices, such as light bulbs and central heating systems that are controlled over the internet, which were hyped for years, are gradually catching on, as the cost of implanting a chip in something falls to almost zero.

Ultra-high-definition televisions were unattainably expensive when they first debuted, now it is difficult to find a set without the feature.

We are possibly so willing to judge new technologies as failures because the rise of free software has raised our expectations for what is considered a success. Facebook and Fortnite became instant hits because there was no barrier to their adoption.

Consumer electronics do not follow the same trajectory.

Even the iPhone, the most revolutionary device of recent times, took a while to catch on: Apple only sold a few million of them in its first year.

That said, it does seem that consumers are ready for the next big thing.

We have definitely hit peak smartphone, if last week's disastrous profit warning from Apple is anything to go by.

So what can we look to for the next piece of life-changing technology?

Gary Shapiro, the head of the association that runs CES, says this year will see a continued focus on everyday items equipped with "artificial intelligence".

But to the extent that is true, it does not say a whole lot.

The term AI is becoming increasingly nebulous, and is not much of a selling point: what matters to consumers is what a new gadget can do, not whether it has AI in the background or not.

The same is true of 5G, of which there will be a lot of hype this week.

The first 5G networks, offering greater speed and more capacity, are coming online in the US and are due to follow in the UK this year.

5G will undoubtedly prove important in future, but it is not as if there is a huge pent-up demand for it today, and as with AI, it is best thought of as a tool that enables new technologies, rather than something to be excited about in its own right.

But there are still developments worth following. Virtual reality and its sister technology augmented reality, which adds a virtual layer to the real world through a phone camera or - in future - hi-tech glasses, have too much potential to be ignored, even if the hype surrounding them has outpaced the real world. Voice control and smart home devices are finally starting to make it out of development and into homes.

The tech industry has so far failed to created a hit product that follows the smartphone. Now, as even Apple struggles to keep the boom going, there is a gap for the next generation of gadgets to fill.