You can set notifications to find out when your collaborators have modified your spreadsheets, and learn what sheets or cells they've modified. You can also choose how often you'd like to be notified.
Some web pages have the Save image As... option disabled on a right click when you try to save an image. Let me show you how to get that image anyway using Firefox.
Today, 40 years ago first public call with a cellphone was made. The cellphone weighed 2,5 pounds (1,1kg) and when it hit the market it would cost you little short of $4,000.