Quick answer: Under a profile in Recommended or Discover, you'll see three heart buttons:
- Heart with a line through it: Dislike/Pass.
- Heart: Like.
- Heart with two lines inside: send an Intro Message.
- You can undo a Dislike/Pass in Discover and Explore, but not in Recommended.
The buttons under a profile
- Heart with a line through it: Dislike/Pass. You're not interested. The profile is removed from your list.
- Heart: Like. Let them know you're interested. If they Like you back, it's a Match and you can message each other.
- Heart with two lines inside: Intro Message. Send a Like with a short note to introduce yourself before you Match. See How to Send an Intro Message
Passed someone by mistake?
In Discover and Explore, you can undo a Dislike/Pass right after you make it. In Recommended, a Dislike/Pass can't be undone.
In Explore
Your choice shows on each member's square: a red heart means you Liked them, and a greyed-out square with a line through the heart means you Passed. See What is Explore and how do I use it?