Some details: http://www.ycombinator.com/apply/

For more details, you can try sending an email to info@ycombinator.com

There's an interview (just getting to that stage is extremely hard). I think that over 50% of those interviewed make it. See the sibling comment for the application process.

Read up on successful applications (google "my yc application" or "succesful yc application").

Some things I believe help making into YC much easier (but not guaranteed):

- Female founders or co-founder

- Very fast and demonstrable traction

- Large potential market

- Founders with successful backgrounds

--

Stuff that won't help on its own:

- Interesting / world changing project (unless you have demonstrable traction). They say they invest in idea-stage companies, I believe that only happens with founders with huge exits on their backs.

Note that this is just my own opinion and I did NOT get into YC and I'm still a BigCo employee.

Sample succesful applications:

https://www.themuse.com/advice/the-muses-successful-applicat...

big list of applications and advice:

https://yourstory.com/2014/10/guide-list-y-combinator/