Background and Identification
Every portable Apple device—from the massive Macintosh Portable to the tiny iPod Shuffle—uses a battery which needs to be charged using an adapter. An AC adapter takes the alternating current from a wall socket and converts it to direct current which can charge a battery.
With the announcement of the MacBook Pro in 2006, Apple introduced the MagSafe connector. The MagSafe connector uses magnets to attach to your computer and can detach when you trip over the cord in the middle of the night. MagSafe was used on all MacBook laptops through 2012 when a slimmer, wider version was introduced, dubbed MagSafe 2. If you want to use an older MagSafe charger with a MagSafe 2 laptop, Apple sells an adapter.
In 2015, Apple began phasing out MagSafe 2 in favor of charging via USB Power Delivery with a new power adapter. This style of charger uses a USB-C connector instead of MagSafe, but is otherwise very similar.
Apple’s MagSafe, MagSafe 2, and USB-C chargers all look like white square bricks and can be plugged directly into a power socket or attached with an extension cable. To identify your adapter, look at the writing on the side of the brick. The number outlined by a rectangle (e.g. “60W“) will tell you the number of watts your adapter can supply. Watts are a measurement of power, and you need enough watts from the adapter to run your laptop. See this page from Apple to find out which adapter style and wattage you need for your computer.
Apple also sells (or sold) smaller devices like the iPod, iPhone, iPad, and Apple Watch which use USB chargers. These smaller white adapters usually plug directly into a socket and have a USB port where you connect your charging cable. To identify your USB power adapter, see this Apple Support page.
Apple Support: Mac laptop chargers
Apple Support: USB Power Adapters
Apple Support: Fast charging
Jordan Merrick: History of MagSafe