Transceiver (SerDes)
Multi-gigabit serial I/O.
Transceivers are hardened serializer/deserializer blocks that move data at speeds fabric I/O can't touch — 6 to 32+ Gb/s per lane. PCIe, 10/25/100G Ethernet, JESD204 converters, DisplayPort and Aurora all ride them. The 'T' in a part number like XC7A100T means transceivers are present (decode yours with the part-number decoder).
Each lane handles clock recovery, encoding (8b/10b, 64b/66b) and equalization in hardware; your fabric sees comfortable parallel words at a couple hundred MHz. Protocol IP stacks on top.