What is a Tide?
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon.
Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request.
### Instruction: What is a Tide?
### Input: 
### Response: Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon.