Link aggregation or LAG is the term used to refer to the technology that lets you bundle multiple physical links into a single logical link. This logical link acts as a single link on a network device.
LAG delivers higher throughput because it uses the aggregate bandwidth of all physical links in a bundle. It also delivers reliability, since in the event of the failure of a single link, the other links remain active and forward traffic.
A term often used interchangeably by Cisco to refer to LAG technologies is EtherChannel.
On Cisco devices, LAT can be configured in one of three ways: