The more, the merrier: Cells have social lives too
There are certain processes that occur inside us that can only happen effectively when our cells are in close contact with each other. Our cells are ALWAYS communicating. Sometimes they check in on each other to make sure everyone is alright (tissue homeostasis), other times they might even team up together to fight an infection (immune response), and sometimes cells come together to make a whole new embryo (fertilisation).
To achieve all these things and many more, cells need to be able to constantly send and receive messages and instructions to each other.