They did not exist a decade ago, but now it is estimated that the price comparison website industry is worth more than a billion pounds a year.
When it comes to making financial decisions, from switching energy providers to buying car insurance, more than six million of us log on to them every month.
The idea is simple: type in what you're looking for and the site instantly collates quotes from scores of different companies, listing them in price order, usually with the cheapest at the top.
They have transformed the way we shop for a string of products and services - saving us the bother of ringing round lots of different companies for quotes.
And the industry is booming - and with around a hundred different price comparison sites out there, it is a bitterly competitive market.
"What we find is that people really struggle to find the best deal, so we look to consumers who are looking to try and get a better deal, who are just trying to save money," she says
"About a fifth of them manage to get the best deal - but a fifth end up paying more. "
So whose responsibility is it to regulate this billion pound industry?
Perhaps surprisingly, while the products sold are regulated, there is no single body dealing with price comparison sites and a recent attempt at self-regulation fizzled out earlier this year.
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