Who
A lot of early Goth bands weren't Goth. They preferred "post punk," especially Sisters of Mercy, who hated the name despite their Gothness. These first Goth bands, Siouxsie and the Banshees, Joy Division, The Cure (whose first record, by the way, is totally not Goth) and Disintegration (who, however, is Goth to the max) shared punk rock's distaste for major labels. Unlike punk rock, Goth acts were not normally very political, which has stayed the same through the present day with bands like Dead Can Dance.

Etc...
How does Goth music sound? Well...most Goth is very sad, slow, introspective and poetic. Many Goth lyrics deal with feelings of futility and helplessness. More punk-influenced bands like Joy Division use more angst-ridden and political themes. Goth music also sounds rich and thick or very minimal and bare. Sexual, depressing, often lovelorn, many other genres of music--like heavy metal, punk, industrial and even pop--have incorporated Goth elements into their music.