Google offers you to support one of the five charities by counting the tabs you open in Chrome.
The total number of tabs opened by users will determine the amount of charitable donations (up to one million dollars) to be made on behalf of the Chrome community.
10 tabs = 1 tree planted
10 tabs = 1 published book
25 tabs = 1 vaccine
100 tabs = 1 square foot of built housing
200 tabs = 1 annual supply of water for one person