Plug n' play components
Some networking tasks come up in almost every multiplayer game: syncing an object's position, keeping animations in sync, or replicating physics. Writing custom sync code for each of these every time would be tedious and error-prone. Plug n' play components let you skip that entirely.
Simply add a component to your object, and it automatically handles the networking for you. Normal examples of this are the Network Transform allowing you to automatically network the position, rotation and scale of an object, or the Network Animator allowing you to automatically sync animations.