fashion photography is when you photograph new and upcoming fashins for magazines and local news. magazines are the most popular kind. store ads too.
There were lots off fashions in so be more specific
A 35mm or medium format DSLR with lenses from 28mm to 200mm for studio work and up to 400mm for location. Strobe lighting and light modifiers i.e. softboxes, reflectors, honeycombs, snoots, gels etc...
in 1780
It brings in income. Photographers can take pictures of a product that is being sold and get it out to the public to be sold.