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A woman chooses Google Search web search engine front page on her tablet.
When you're online - shopping, browsing, playing games - advertisers are watching your every move. They want to know what you're doing so they can target ads directly to you.
Traditionally, they use little bits of code known as third-party cookies, but Google is considering something completely different.
For more we turn to Alistair Barr, he's the senior technology reporter for USA Today.