The Brontë sisters - help needed fast!

I've been trying to find information about what kind of impact the Brontë sisters had on English literature but the same phrase "they had a great impact on English literature" keeps appearing everywhere and no one has really been able to explain to me what that means. I really wish someone could help me out here and tell me how they influenced the direction of English literature. I'd be really grateful.

I have only read Wuthering Heights by Emily, and what it said in the preface is that this book was the first to use this particular narrative form with present and past alternating and even meeting each other at some points.

Thanks a lot! I've read Wuthering Heights but it didn't have the preface so I didn't know that.
I bet there are other things too so If someone knows anything else...

Both Emily and Charlotte are influences of Virginia Woolf, Charlotte had a bigger impact social-wise, because of her feminist influence, the Bronte sisters are among the first female romance writers of some success.
Also, they have an overall impact in the formation of the structure of XIX century Romance.
Emily is one step ahead, because of time/space experience in her narrative and the bigger psychological trait of her characters (mainly heatcliff) and how it also reflected in the descriptive nature of her book.