Factor. \[ y^{2}-36 \]

Step 1 ：This is a difference of squares problem. The difference of squares formula is a^2 - b^2 = (a - b)(a + b). In this case, a = y and b = 6.

Step 2 ：So, we can rewrite the expression as (y - 6)(y + 6).

Step 3 ：\(\boxed{(y - 6)(y + 6)}\) is the factored form of the expression \(y^{2}-36\).