Songbird

Songbirds are the main group of birds in the order Passeriformes. They are the suborder Passeri, sometimes called 'oscines' (Latin for songbird). They are a genuine clade.
There are about 4000 species of songbird. Their syrinx (vocal organ) is able to produce varied and beautiful singing. They are a very successful group of birds, in fact they are the dominant birds on Earth today.
It seems songbirds evolved 50 million years ago in the part of Gondwana which later became Australia, New Zealand, New Guinea and Antarctica. They then spread around the world.
Song
Their song is mainly territorial: it communicates the identity and whereabouts of an individual to other birds of the same species. It also signals sexual intentions. Female preference in some populations is based on the extent of a male's song repertoire. The larger a male's repertoire, the more females a male individual attracts.
Bird calls are also used for alarms and contact. They are especially important in birds that feed or migrate in flocks. Although almost all birds give calls of some sort, well-developed songs are only given by a few lines outside the songbirds.
Families
Corvida
This is now known to be a paraphyletic group and so it is not used in modern systematics.
Menuridae
Menuridae: lyrebirds
Atrichornithidae: scrub birds
Bowerbirds and Australian treecreepers
Ptilonorhynchidae: bowerbirds
Climacteridae: Australian treecreepers
Meliphagoidea: honeyeaters and allies
Maluridae: fairy-wrens, emu-wrens and grasswrens
Meliphagidae: honeyeaters and chats
Acanthizidae: pardalotes, scrubwrens, thornbills, and gerygones
Australopapuan babblers
Pomatostomidae: Australasian babblers
Logrunners
Orthonychidae: logrunners
Other basal lines
Cinclosomatidae: whipbirds and allies
Neosittidae: sittellas
Pachycephalidae: whistlers, shrike-thrushes, pitohuis and allies
Dicruridae: monarch flycatchers and allies
Campephagidae: cuckoo shrikes and trillers
Oriolidae: orioles including figbird
Artamidae: woodswallows, butcherbirds, currawongs and Australian magpie
Paradisaeidae: birds of paradise
Corvidae: crows, rooks, ravens, magpies, and jays
Corcoracidae: white-winged chough and apostlebird
Irenidae: fairy-bluebirds
Laniidae: shrikes
Vireonidae: vireos
Passerida
This is accepted as a clade.
Petroicidae: Australian robins
Alaudidae: larks
Chloropseidae: leafbirds
Aegithinidae: ioras
Picathartidae: rockfowl
Eupetidae: rail-babbler
Bombycillidae: waxwings and allies
Ptilogonatidae: silky flycatchers
Cinclidae: dippers
Motacillidae: wagtails and pipits
Prunellidae: accentor
Melanocharitidae: berrypeckers and longbills
Paramythiidae: tit berrypecker and crested berrypeckers
Passeridae: true sparrows
Estrildidae: estrildid finches (waxbills, munias, etc.)
Parulidae: New World warblers
Thraupidae: tanagers and allies
Peucedramidae: olive warbler
Fringillidae: true finches
Cardinalidae: cardinals
Drepanididae: Hawaiian honeycreepers
Emberizidae: buntings and American sparrows
Nectariniidae: sunbirds
Dicaeidae: flowerpeckers
Mimidae: mockingbirds and thrashers
Sittidae: nuthatches
Certhiidae: treecreepers
Troglodytidae: wrens
Polioptilidae: gnatcatchers
Paridae: tits, chickadees and titmice
Aegithalidae: long-tailed tits
Hirundinidae: swallows and martins
Regulidae: kinglets
Pycnonotidae: bulbuls
Phylloscopidae: leaf-warblers and allies. Recently split from Sylviidae.
Sylviidae: Old World warblers
Hypocoliidae: Hypocolius
Cisticolidae: cisticolas and allies
Icteridae: American blackbirds, New World orioles, grackles and cowbirds.