Subject: What are some examples of energy converting to matter?

I know of many examples of matter converting into energy: nuclear 
reactions, particle annihilation, etc.  However, I don't know of 
any examples of energy transforming into matter. I mean, it has 
to happen, right? And how does it happen (are there theories or 
is it known?)?

You can be pretty detailed because I have some good understanding 
of physics for my age.  I have read Hyperspace (Micho Kaku), A 
Brief History of Time (Hawking) and few others.

Thank you for your help and your time.  This is really 
appre

Re: What are some examples of energy converting to matter?