In that blog post, and in a technical note sent to data protection authorities the same day, we said that while Google did collect publicly broadcast SSID information (the WiFi network name) and MAC addresses (the unique number given to a device like a WiFi router) using Street View cars, we did not collect payload data (information sent over the network). But it’s now clear that we have been mistakenly collecting samples of payload data from open (i.e. non-password-protected) WiFi networks, even though we never used that data in any Google products.