Frame aggregation is a feature that allows communicating on a shared link or channel, typically a TDM shared channel, with a minimum time slot that for efficiency reasons benefits from filling the time slot with data, i.e. sending two or more data frames in a single transmission.
The feature is an important part of the IEEE 802.11e, 802.11n and 802.11ac wireless LAN standards that increases throughput with frame aggregation.
The MoCA protocol used for communication over coaxial networks also implements frame aggregation for the same reason.
The article uses IEEE 802.11 as a basis for explanations as it is probably the most wide spread and commonly known shared channel communication solution, but the protocol features for frame aggregation are common to many other communication protocols that utilize a shared communication channel, e.g. MAC service data unit (MSDU, e.g. an Ethernet frame) aggregation and MAC protocol data unit (MPDU, e.g. IEEE 802.11n frame) naming is also used in MoCA.
This mechanism allows each of the aggregated data frames to be individually acknowledged or retransmitted if affected by an error.