You might think ''junk mail'' but the pamphlet in your letterbox addressed ''to the homeowner'' is probably there for a reason.
It may not name you, yet the company behind the pamphlet trying to win your business knows about your suburb, and your spending habits.
"Big Data" is the latest technological advance in how companies market their products to consumers. This technology utilises a number of data sets stripped of people's names, including supermarket loyalty card data and bank transactions.
But the trend has also opened up myriad privacy concerns.
Peter Coroneos, former head of the Internet Industry Association, said consumers are surrendering more information about themselves than they realise.
"A lot of these fears actually evaporate when Australians understand the limits of how this information may be used, but they also need to know the risks,'' he said.
For a year the natural gas company Jemena monitored four sets of data - including ABS data and NAB data on transactions - to target potential customers.
"We're able to use those assumptions and then use those for the next year," said Lauren Fried, founder of Pulse Marketing, which works for Jemena.
"You need to find what is that matrix to decide how you're going to target your message."