Define: cold calling

I know that the Philippines is the call center capital of the world. While I tried to push my career towards applying to some call centers before, I admit I'm a complete dumb with most of their terms. And one of them is "cold calling"

According to Wikipedia,

Cold calling is the process of approaching prospective customers or clients, typically via telephone, who were not expecting such an interaction. The word "cold" is used because the person receiving the call is not expecting a call or has not specifically asked to be contacted by a sales person.

If it's not for one of my tasks now, I won't look for the meaning of this. But I'm glad that I learned something today!