ok here is the just of what pic chips are
Say you have a basic avoiding obstacles robot once the sensor is triggered by an object it sends a signal the pic chip pic up the signal and dose what ever you programmed it to e.g. tells the left motor to stop causing the robot to turn left you program a pic chip by plugging it into your computer with a pic chip board (comes with a pic starter kit) and you flash it with the program that u wrote (software to write program also comes with a starter kit) its might sound tricky but its not
A PIC is a microcontroller. Basically its a processor (remotely similar to the cpu in your computer) but a whole lot less of a unit. If you are interested in this concept and have a little bit of money to spend (under $300) i'd recommend getting a Mindstorm Robot from Lego. They have a Hitachi chip in them. They are not a PIC but similar. The first thing i recommend is blowing up the os and byte code that comes installed on it and installing BrickOS (brickos.sourceforge.net) i recommend using linux, but there are cygwin programs out there and setup files to help you get setup to do this in windows.
You can do quite a lot with the mindstorm, like test said, you can make it avoid obstacles, you can write AI code to make your robot learn to go thru a maze and a whole lot of stuff. Dont like the concept of making a vechicle limit your creativity.
The mindstorm is programmed via a IR tower and a IR receiver in the "Brick" which constains the processor, batteries, sensor inputs and motor output plugs.
If you have over $300 to spend i'd lookup MIT's Handy Board, which is what the Mindstorm is based off of.
From the Internet I heard people that are interested in robotic are into PIC programming
That's not true although you can use PIC but its not advisable. I did robotics and artificial intelligance and have built and designed certain commercial robotics systems over the years. The best way to design robotics is to disect its main functions and program them. There are two robots the manned and unmanned. The unmanned requires heavy knowledge in something called fuzzy logic.
Basically you can use a lot of robots using simple processing knowledge. The simplest would be the Motorolla M68HC11. I have used this processor for many robotics systems and have had good progress and if you want to start something like that, i would recommend that you use that chip first although it is an old chip, it would provide a very good grounding knowledge for you.
For some reason i love the manned ones. They are of course simpler but also you can use a lot of systems like the card system of designing. For example there are a lot of famous manned robotics like the pathfinder but the thing i love about robotics is the sky's the limit for your imagination
Now a days, i do programming and don't do much robotics but i still have the passion for it