Every little move we make, someone is watching - especially in a supermarket.
Each time we reach for an expensive bottle of olive oil or the cheapest home-brand tinned tomatoes, we become a little dash of data. And all those little bits of data add up to ''key customer insights''.
We are a contrary lot, happy to spend top dollar for some things but reaching for the cheapest item when it comes to others. Our changing behaviour means the ''death of trends but the rise of micro-trends'', according to David Chalke, of Quantum Market Research.
The major supermarkets pay a lot of attention to this type of data and never more so than at Christmas. Most people now are still thinking about how economical a chuck steak casserole can be, but the supermarkets have turned their attention to the time of year when we dig deeper into our wallets.
Christmas is critical for gladiatorial combatants Woolworths and Coles. They are rolling out the big guns for the battle ahead.
In the Coles corner, expect to encounter British chef Heston Blumenthal, the master of kitchen wizardry, while Woolworths will launch a private-label range called Gold. The premium offering can be compared to Tesco's Finest range, according to Woolies.
The premium market is where both companies are especially keen to help us part with our cash.
Amanda Green, in charge of seasonal innovation at Coles, categorises Christmas shoppers into three groups - creative planners who make beautiful, magical events; routiners who prepare the same festive meal year after year; and last-minute maniacs who do one large shop when Santa is on the doorstep.
You won't get the bonbon trinket for guessing it's the creative planners supermarkets like most. For these customers, taste, presentation and provenance are important. So this year, expect to find RSPCA-approved ham and free-range turkey at Coles. Plus Blumenthal's special range.
Home-made is big this year so there will be kits for kids in the kitchen, edible table pieces and a wattleseed Christmas cake.
We may love cooking but hors d'oeuvres confound us, so these will come ready-made along with party nibbles.
The big flavour trend? Salted everything. There will be salted caramel bombes, mince pies and ice-cream.
Woolies hopes to come home with Gold range items such as all-butter mince pies, puddings with candied orange and almond-encrusted panettone.
Christmas comes but once a year and with Australians' recent shift to thrift, there are savings to be plundered.