Google recently outlined plans to disable a tracking technology in its Chrome web browser.
And Facebook said last month that hundreds of its engineers were working on a new method of showing ads without relying on people's personal data.
The developments may seem like technical tinkering, but they were connected to something bigger: an intensifying battle over the future of the internet. The struggle has entangled tech titans, upended Madison Avenue and disrupted small businesses. And it heralds a profound shift in how people's personal information may be used online, with sweeping implications for the ways that businesses make money digitally.
At the center of the tussle is what has been the internet's lifeblood: advertising.
More than 20 years ago, the internet drove an upheaval in the advertising industry. It eviscerated newspapers and magazines that had relied on selling classified and print ads, and threatened to dethrone television advertising as the prime way for marketers to reach large audiences.