$\displaystyle \lim_{n->\infty } (1-\frac{1}{2^{2}})(1-\frac{1}{3^{2}})...(1-\frac{1}{n^{2}})$

Can someone please help me out here? Have never find the limit of a function like this. I've learned limits but not this kind, if someone could tell me the first steps in those kind of tasks, would be great.

Thanks,

Flamuri