No need to paraphrase what the App is all about so here’s straight from their website:
Stache makes it quick and easy to collect and re-discover pages you find useful, interesting or inspiring, in a beautiful, visual and fully searchable library.
I use to utilize Zootool in a similar way until it shut down. The way Zootool differed from Stache is that the former saved individual images of your choosing from a website rather than entire pages like Stache does but the premise is somewhat the same for me as far as how I used both. I use Stache primary to save website’s from photographer’s who’s work I really admire. There’s a larger chance of recalling I have this ongoing curation of inspirational goodies in this App than if I were to bookmark them in a folder in Safari. It’s all about visual bookmarking and the fact that it syncs seamlessly with its iOS App is stellar.