The words "slut" and "whore" are often hurled at women as insults. I think we need to put an end to this but rather than eliminating these words from our vocabulary, I say we should reinvent them.
Women should feel free to self-identify as sluts if they so choose. Wear your slut badge with pride and don't let anyone put you down or make you feel less than because you are a slut. Being a slut is not a bad thing at all. It's inherently neutral.
There is nothing wrong with having no sex. There's nothing wrong with only having sex with one partner. There's nothing wrong with having lots of sex with lots of different people. It's a woman's choice what she wants out of her own sex life.
If someone trusts you enough to be open about their sexual history with you, you should never shame them for the number of partners they have had. For some people, their sex life is a very private thing. For others, it's a topic on the table for discussion. It's important to respect both types of people.
The bottom line: your sex life has nothing to do with your worth. I know some pretty awesome people who haven't had their first kiss and I know some pretty awesome people that have had 20 different partners.
What matters is how you treat people. If you had sex with 20 different people and afterwards you told them all that they were ugly and then took all the cash out of their wallets and burned their clothes so they had to walk home naked, then there is an issue. But if you treated each of your partners with respect and human decency, it doesn't matter how many there were.
So be kind to others, be accepting, and don't judge people based on choices they make that don't affect you.