What is a Smartphone? Do I NEED a smartphone?

Over the past half year relatives and friends have been changing their phones and getting either Blackberries or iphones or Ainos, all of these, I think, are smartphones but I didn't know what a smartphone is so I had a look on the net and in fact it is pretty easy to understand:

From videojug:

What is a "smart phone"?

A smart phone is any device that has an operating system that you can install programs into, as well as being a personal information manager; managing your contacts, your calendar, your tasks, and your memos. It allows you to listen to music and play video games, and it's really just an all-in-one multimedia device.

But in the end what should I chose? Do I really need all of these things? I have a phone. I have a mac. I have a GPS. I have a camera so in fact I have everything that I need so do I need a smartphone?

Talking about phones there is a good video here:

Here are my phones!