You always have the Find Familiar spell prepared, and you can cast it in 10 minutes without a spell slot or components. The spell is improved in the following ways when you cast it.
Expanded Options
You can choose one of the normal forms for your familiar or one of the following special forms: Death Snail, Flying Book, Homunculus, Mock, Moon Jelly, Pet Rock, Pseudodragon (can't use its Sting), Rag Doll, Tin Soldier, and Winter Wolf Pup.
Witch Familiar
The familiar's stat block is improved, as detailed in the Witch Familiar sidebar.
Synchronized Turns
Your familiar takes its turn immediately before or after your turn each round (your choice).
Quick Attack
Once per turn as an action or Bonus Action, you can command your familiar to take the Attack action (one attack only) on its turn.
Spell Channeling
When you cast a spell with a range other than Self on your turn, you can cast it as if you were in your familiar's space. The familiar must be within 100 feet of you, and it must take a Reaction to deliver the spell when you cast the spell as normal.