The YouTube search history of Europeans is at the center of a major face off between the web's most powerful company and the European Commission. Six European data agencies launched investigations into Google this week in an action coordinated through a Working Party established by the Commission. The action pivots on the data that Google collects from users of its services, data such as location, emails, and search histories.

Data is Google's main asset, and the European governments want to curtail how Google can use it. They are pushing for two changes in particular. First: that users are informed where and for what purpose any data taken will be used. For example, whether information entered in email service Gmail will affect results in Google Search Engine. Second, the European governments want Google to offer users the choice to opt-out of data collection.

The problem started with the merger of Google's 60-plus separate privacy polices in March 2012, which allowed Google to share data collected on one service with all its services. European data agencies say that leaves users unclear as to whether and how data taken on one service will be used in another.

Targeted adverts are how Google makes money on its free services, and data is what Google uses to target the ads. Google made $43.7 billion from targeted advertising last year, out of total revenues of $46 billion.

The changed privacy policy will have contributed to the 20% year-on-year rise in ad revenue that the company saw between 2011 and 2012, says Mark Little, principal analyst at Consulting Group Ovum.