Thunderbolt is a newer connectivity standard for all Macs, and it’s useful for connecting different kinds of peripherals, including displays - even in a daisy chained way. USB 3.0 is much faster than USB 2.0 (so avoid USB 2.0 drives). USB 3.0 is a widely-used standard that will let you plug your hard drive into most any Mac or PC with a USB port. The hard drive answer starts with two key connectivity options: USB 3.0 and Thunderbolt. With dozens of external drive options, how do you find a good external hard drive for Mac?
Better yet, a good external drive will let you create a full system backup copy of your drive.
Because Apple is so stingy with storage - you get just 128GB in the entry-level MacBook Air and MacBook Pro - having a good external hard drive for Macs is important for offloading your large video and photo files.