FPGA

Field Programmable Gate Array

This is silicon chip that consist of configurable logic blocks. Between these blocks you have re-configurable wiring circuitry .

In the same chip you can also run two parallel process

It has I/O pins to interact i/p with outside world

Now suppose you have to create your dsp processor that takes some input and then filter it to give analog output.

For that beside FPGA you need two more IC's .one is ADC foe i/p and other is DAC for o/p beside FPGA.you have to do a verilog programming for your filter circuitry in FPGA.

and in case you have to do something by sensing temperature then you need temperature sensor ,FPGA and some output device say fan and in FPGA you have to do programming for PID controller. Now here in a same FPGA silicon chip you can create many PID controller and then run them parallel

CPU is also similar to FPGA

FPGA runs a system with dedicated block. say multiple PID controller. Actually FPGA has many dedicated block that not necessarily sharing resources for any given task

But

CPU figure how to sequentially come up with the sequence of instruction and then processor just start executing each function one at a time. i,e processor is good to do many different things at a same time.by sequentially executing instructions.

Also In FPGA we do Programming in Verilog to tell the expected Behaviour of a circuit and after that we see the RTL circuit and implement that Circuit indirectly through code in FPGA .in the video shown below you will see the power of FPGA over Microcontroller. That is do awesome pulse width modulation on display in order to display a image you need an FPGA or a sought of processor that too will be designed by an FPGA apart from microcontroller.

Other than FPGA there is also a CPLD (Complex Programming Logic Device) which is similar to FPGA except a difference that in CPLD we do programming in VHDL rather than Verilog. Also to improve your knowledge once again remind you that these languages are not sequential ..that is doesn't have loop ,break ...etc kind of things rather you just write a code just to design your hardware which will be automatically implemented on your FPGA through automatically wiring in it.

Watch Video from 15:17   To Know a Power of FPGA over Microcontroller

Some FPGA Projects

--you can built awesome things with FPGA if you use CPU say I7 which is connected to internet via ethernet.Also if you feel in current technology something is taking a lot of time to encrypt or decrypt data then you can use FPGA for your projects .or you can create your own inovative protocol and test it in FPGA.Each pin of FPGA is ready to act as a protocol . 

Follow a chart shown below in order to understand what makes FPGA so special

you can find from above chart that

control flow stuff means all if ,else stuff.in fpga it is challenging as here you need to make a state machines

io in Fpga you have 600-700 io that you can use

Timing Control-FPGA has a good control on timing control .if you want to make violation in setup time and hold time of registers then you can do that using fpga.

GPU is really good in floating point

FPGA is really good in its i/p o/p pins. Do you Know i/p pin speed is b/w 400-800 mb/s with its shift register which makes it a lot better than even Intel I7 processor and o/p pins that is transceiver pins can give data between 1-->25 gb/s . WOW! . but at the same time doing programming in FPGA is challenging as it uses Verilog. So you have to little conscious and ready to sophisticate while programming.

Only 4500 Rs FPGA from Actel Worth Buying it as it is arduino compatible. [Click Here] 

Note: Costly FPGA has a feature of PCI core ....Learn What is a PCI coree.As far as I know good PCI core is that which interfaces FPGA with computer very fast.

30 euro's is a lower bound cost of a FPGA with which you can do some interesting things.