Google Finance and Apple’s Stocks app have added new features over the years to make them more useful for tracking the markets and your investments.

Ten U.S. states have legalized systems that can be plugged into standard wall outlets. The technology typically does not require permits or electricians.

© Poppy Lynch for The New York Times

Ten U.S. states have legalized systems that can be plugged into standard wall outlets. The technology typically does not require permits or electricians.