When we talk about defining a function, it can be tricky. Here are some important points to remember:

• Unique Output: Every time you put in an input, it should only give you one output. This can be tough when it looks like you could get more than one answer.

• Input-Output Relation: The connection between inputs and outputs can be complicated. It needs some careful thinking to understand it.

To make things easier, you can use tools like mapping diagrams or tables. These help you see how inputs and outputs are related and ensure that each input gives a unique output every time.