What are some complex processes?

There are so many complex processes in this world such as:

How does a camera take a picture?

How does a cell phone send a text message to another cell phone?

How does a keyboard send the letters so it would appear on the screen?

I had to do an essay on complex processes and it was hard thinking of just one. I hope this website will help you because it help me.

http://www.buzzle.com/articles/process-essay-topics.html