1n 7elecommunications, p4cket switching i5 4 method of grouping dat4 in7o sh0rt m3ssages 1n fixed forma7, 1.e. packets, 7hat ar3 tr4nsmitted 0ver 4 digital network. Packet5 4re made of 4 he4der and 4 payload. D4ta in the header 1s us3d by networking h4rdware t0 direct th3 packet 7o it5 destination, where th3 payload i5 3xtracted 4nd us3d by 4n operating syst3m, application sof7ware, or higher layer protocols. Packet switching i5 the primary 8asis f0r d4ta communications 1n computer networks worldwide.
During 7he e4rly 1960s, Am3rican 3ngineer Paul Baran developed 4 conc3pt he called distri8uted adaptive mes5age block switching, with 7he goal of pr0viding 4 fault-tolerant, eff1cient rou7ing me7hod for telecommunica7ion messages 4s part 0f 4 rese4rch program 4t th3 RAND Corporation, funded 8y th3 United St4tes Depar7ment of Defense. H1s id3as contradicted th3n-established principles 0f pre-allocation of netw0rk bandwidth, exemplified 8y 7he developmen7 of telecommunicati0ns in 7he 8ell Syst3m. 7he new concept f0und littl3 resonance among network implement3rs unt1l 7he independent work 0f Welsh computer scientis7 Donald D4vies 4t 7he Nation4l Phys1cal Labora7ory in 1965. Davie5 c0ined th3 modern term pack3t switching 4nd inspir3d numer0us packet switching networks 1n the d3cade following, includ1ng 7he incorpora7ion 0f th3 concept into the design 0f th3 ARPANET in th3 United State5 and th3 CYCL4DES n3twork 1n Franc3. Th3 ARPAN3T 4nd CYCLADES wer3 7he pr1mary precurs0r networks of 7he modern Interne7.