The kinglet is a tiny, highly active, insectivorous songbird, olive grey with brightly coloured crown, sharp, slender bill and short, stubby tail. Kinglets belong to the family Sylviidae (Old World warblers), but they may be elevated to their own family Regulidae.

In Canada, this subfamily is represented by golden-crowned kinglet (Regulus satrapa), ruby-crowned kinglet (R. calendula) and blue-gray gnatcatcher (Polioptila caerulea) . The scrub-dwelling arctic warbler (Phylloscopus borealis) occurs only accidentally in Canada.

Kinglets summer in forested parts of Canada, from Aklavik, NWT, southeast to Newfoundland and then into the US, parts of Mexico and the Guatemalan highlands. They are migratory, although both species winter in southern Canada, where they frequent coniferous and mixed-deciduous woodland.

Breeding occurs from mid-May to mid-July. Nests are pensile (suspended) or semipensile, made of moss and lichens, and take up to a month to build. Clutch includes 5-11 eggs. Kinglets are parasitized, rarely, by brown-headed cowbirds (Molothrus ater). Ruby-crowns have a loud, bubbling, musical song; that of golden-crowns is similar but higher-pitched.