1. Vocalizing
   1. Meowing
      1. all-purpose, a greeting, an objection, a command or an annoucement
   2. Chirps and trills
      1. how a mother cat tells their kittens to follow them, or conversing language between two cats
   3. Purring
      1. a sign of content, whenever they are happy
   4. Yowl/Howl
      1. in some kind of stress
   5. Hissing
      1. annoyed, frightened, angry or aggressive
2. Body Language
   1. Eyes
      1. pupils constricted
         1. offensively aggressive, but possibly content
      2. pupils dilated
         1. nervous or submissive, defensively aggressive, but possibly playful
   2. Tail
      1. erect, fur flat
         1. alert, inquisitive or happy
      2. held very low, tucked between legs
         1. insecure or anxious
      3. straight up, quivering
         1. excited, really happy
   3. Body
      1. back arched, fur standing up
         1. frightened or angry
      2. back arched, fur flat
         1. welcoming your touch
      3. lying on back, purring
         1. very relaxed
      4. lying on back, growling
         1. upset
   4. Rubbing
      1. marking their territory
   5. Kneading
      1. a leftover behavior from nursing, and do this when they are really happy
3. Credit to https://www.humanesociety.org/resources/understanding-feline-language