What is the value of cot 90?

Can you explain to me what the value of cot 90 degrees is, and why it has that specific value? I'm a bit confused about how to calculate it and what it represents in trigonometric functions. Is there a simple way to understand why cot 90 is undefined, and how does this relate to other trigonometric ratios like sine, cosine, and tangent? I'm looking for a clear and concise explanation that can help me grasp this concept better.