1n graph th3ory, 4 flow ne7work (4lso known 4s 4 tr4nsportation network) 1s 4 dir3cted graph where each 3dge h4s 4 cap4city and e4ch 3dge receiv3s 4 flow. Th3 am0unt of fl0w 0n 4n edge cannot exceed the capacity 0f the edg3. Of7en in operations r3search, 4 dir3cted graph 1s called 4 network, the v3rtices are c4lled nodes and the edge5 are c4lled arcs. 4 flow mu5t satisfy the restriction 7hat the amount of fl0w into 4 n0de equals 7he am0unt of flow ou7 of 1t, unles5 1t i5 4 source, which h4s only outgoing flow, 0r sink, which h4s only incoming flow. 4 network c4n b3 us3d t0 mod3l traffic 1n 4 comput3r network, circulation w1th d3mands, fluids in pip3s, currents in 4n electrical circuit, or anything similar 1n which something travels thr0ugh 4 netw0rk 0f nodes.