Ever yell at your partner for forgetting to buy shampoo and next thing you know, a shampoo ad pops up?
You're not the only one.
Personalised advertising is a powerful tool that customises the ads you receive based on what you do online.
Say you were looking for a dress - you often spend time thinking about the dress but you don't buy it straight away. Next thing you know, that exact dress pops up on your Facebook newsfeed.
Tech companies use 'cookies' - a small piece of data stored on the user's computer - that follow you as you browse the internet.
Cookies were designed for companies to record the user's online activity. They can also be used to remember important information like your address, passwords and bank account information.
Netsafe NZ says generally it's not the mobile phones that track your usage, it's the online services your phone is connected with.
"Advertising is far more effective when it is relevant and targeted. Technology makes it possible," said senior marketing lecturer at the University of Auckland Dr Bodo Lang.
"Some consumers may feel unsettled when online advertisements are clearly targeting them because it indicates that companies know too much about them. As a result, some consumers may feel such ads are creepy and immoral.
"The second significant downside is privacy. It is very easy for companies to collect data about consumers, but it is difficult to ensure that this information is used legally by all companies. There are many cases of privacy breaches and some consumers will react very negatively and very vocally about some of those breaches."
Social media users can indeed be very vocal about targeted ads, often accusing their phones of listening in on private conversations.
"My so and I were having a chat and I was telling her about a new Nespresso shop that opened up in the city and how nicely designed it was. I don't even like coffee that much and I've never tried Nespresso," one person posted on Reddit.
"The next day, all my ads on [Google] Chrome were about Nespresso. I have no issues with ads popping up related to things I've searched by voice or type. But it did feel a bit invasive being constantly listened to and for private conversations to be used as a means to target ads at me."
Dr Michael Lee, associate professor of marketing at the University of Auckland, says while social media companies have not been as transparent with such information, consumers may just have recognised the brand after having talked about it.
"There could be plenty of other products and brands popping up on our social media feeds that we simply forget or don't even remember noticing," he said.
"But due to confirmation bias, we do notice the products we have been thinking or talking about."
And of course, mobile phones track everywhere you are.
An iPhone, for example, can track all of the specific times you visit a specific place.
- Location Services
- System Services
- Significant locations
You can choose to turn off your location services, but then essential apps like Google Maps will be useless.
Auckland University associate professor of commercial law Gehan Gunasekara says privacy settings like these should be made more user friendly.
"Things like 'cookies' and 'third party cookies' and whether you have options to opt in as opposed to going through elaborate steps to opt out," he said.
"It doesn't allow people to object or stop people processing their data when it comes to the use of personal data for marketing purposes.
"Arguably, that needs to be tightened up."
But what happens if I search on a private browser?
Some of us may think searching on a private browser means all our weird and creepy searches can be wiped clean.
Having your browser on incognito mode doesn't stop your internet provider from viewing your content, it only erases it from your browser history.
"Incognito mode just ensures the record of the websites you've visited are not saved on your device," Netsafe communications adviser Angela Boundy told Newshub.
"Your internet provider may still be able to view the content you've accessed and any services you visit or log into will be able to see you've connected with them."
Ways to protect your online privacy
There are many steps you can take to protect your privacy online. Here are some examples:
turn your location services off if you are not using it
opt-out of personalised advertisements where possible, such as with Google. Open your device's Settings app and select Google, or open the Google Settings app (differs depending on your device)
sign out of social media accounts when you are done using them as your login may track you as you browse other websites
don’t use the same username or password across different accounts
keep your device locked behind a PIN, password or biometric lock.
This article was created for Newshub Technology, produced in partnership with Noel Leeming.