How to beat the Hollow Knight Silksong Widow

How do you beat the Silksong Widow? This boss has the population of Bellhart caught up in its sticky web, and it'll take all your efforts to ensure that Hornet doesn't join them. She's relentless, and her aggression is enough to give the most seasoned Hollow Knight veterans a run for their rosaries.
Widow is one of the main Silksong bosses, so there's no getting around it - if you want to progress in the Metroidvania game, you have to beat her. It's also the main condition to save Bellhart in Silksong and rescue the townsfolk from Widow's silken threads. Thankfully, we've got her exact location on the Silksong map and all the best boss strategies you need to beat her.
RELATED LINKS:
Every Hollow Knight Silksong crest and where to find them
Hollow Knight Silksong map, area order, and Shakra locations
Hollow Knight Silksong flea locations - The Lost Fleas quest guide