Go function signatures define inputs and outputs using the syntax func Name(params) (returns) with explicit types.
Go function signatures follow a consistent pattern: func Name(params) (returns), where parameters and returns are optional and must be explicitly typed.
// No params, no return
func Greet() { }
// Params with types, single return
func Add(a, b int) int { return a + b }
// Multiple returns (common for error handling)
func Divide(a, b float64) (float64, error) { }
// Named returns (auto-returns if bare return is used)
func Echo(msg string) (result string) { result = msg; return }
A function signature is the blueprint that tells Go exactly what inputs a function needs and what outputs it will provide. It matters because Go requires you to declare these types explicitly, preventing accidental mistakes before your code runs. Think of it like a restaurant menu: the signature lists the ingredients required (parameters) and the dish you will receive (return value).