Short answers, pulled from the story.
The first magical girl anime is Sally the Witch, produced by Toei Animation in 1966. Its anime adaptation introduced the idea of using a compact to transform, a device that became a recurring feature of the genre.
Sailor Moon, whose anime ran from 1992 to 1997, introduced the transforming heroine format borrowed from tokusatsu hero shows like Super Sentai and Kamen Rider. It replaced the lone magical girl with a team and shifted the genre from comedic plots to action-driven stories centered on femininity as a source of power rather than vulnerability.
Majokko was the term used for the wave of magical girl series produced mainly by Toei Animation in the 1970s. The term magical girl (mahō shōjo) came into use starting with Toei's 1980 release Lalabel, the Magical Girl, and largely replaced majokko after the success of series from other studios such as Magical Princess Minky Momo (1982) and Creamy Mami (1983).
Notable Western examples include W.I.T.C.H. (2001) and Winx Club (2004) from Italy, and Totally Spies! (2001), LoliRock (2014), and Miraculous: Tales of Ladybug & Cat Noir (2015) from France. American animated series including The Powerpuff Girls (1998), Steven Universe (2013), and Star vs. the Forces of Evil (2015) also drew on magical girl themes.
The growth of late-night anime broadcasting in the early 2000s opened space for series with mature themes aimed at older male viewers. Magical Girl Lyrical Nanoha (2004), a spin-off of the adult game series Triangle Heart, was an early prominent example. The format allowed darker themes such as death and the cost of magical power to be explored.
Merchandise has been central to the genre since Himitsu no Akko-chan, described as the earliest series with a toy line and a huge hit. Scholar Kumiko Saito characterized magical girl anime as twenty-five-minute advertisements for toy merchandise. Pretty Cure became Japan's fifth highest grossing franchise as of 2010 largely through merchandise sales, with Bandai as a key producer for both that series and Sailor Moon.