How comparable is the Arduino circuit board to actual circuit boards?

First, let me give you an idea as to what an Arduino actually is. Arduino is just another Atmega development board. You can find many other circuits like Arduino aimed at the exact same market. What makes Arduino so successful is that it is open source and it has a lot of community support. An Arduino consists of a microcontroller (which is basically a very compact computer, an Atmega328, in your case), all the circuits required to run it (like a power regulator, a USB to Serial Convertor chip) and a software package (i.e. the notepad like GUI and all the libraries). "Actual circuit boards" can be of many types. Some can be purely analog (like amplifiers for your speakers) or hardwired digital (like some remote controls or old washing machine controllers, but mostly old stuff) or some may have small computers similar to ones found in your Arduino. The circuits which have microcontrollers are categorized as embedded systems. When an engineer designs an embedded system, he will first try out his design on a ready made "development boards". These boards are similar to your Arduinos, except mostly, they are not Arduinos. This is proof that his concept works. After testing his idea and he moves to production level design. Here, he will design all the circuit to the exact specifications. E.g. he may shrink it, make it more robust, make it cheaper etc. So, basically when you use an Arduino, you can, at max, build a prototype. Since you are just starting, Arduinos are fine. But, I would suggest that you don't stick to them for a long time, because they are a bit dumbed-down. The Arduino IDE has built-in (and downloadable) functions to implement most of your code for you. So, you miss out on many key concepts. However, I would suggest that you take a look at this site: http://www.javiervalcarce.eu/wiki/Program_Arduino_with_AVR-GCC As for Adruino Sensor, to tell you the truth, most of these sensors exsisted even before Arduinos were conceived. They are just repackaged are "Arduino Sensors" by eager sellers who want to hop on the Arduino Bandwagon.

Thanks for the A2A scott..... coming to your question,  "The aim of aurdino team is to make a device that is technically simple and accessible to a large group of people with diverse technical backgrounds." yes, you are right. Arduino simplifies the process  a lot. But,if you are actually trying to learn electronics,no that is not the way how you learn electronics........ Aurdino is for some one 1.)who wants to build something in electronics but don't have an idea of how things work inside actually, but is in badly need of a device which he needs to do a particular work. (or)  2.)wants to build something instantly with electronics and enjoy the excitement that comes on seeing the device work. But,contrary to the above 2 points,if you are a beginner, it boosts up your confidence a lot and gives you enough confidence to kick off with understanding of electronics........... what you are learning is application, and yes that will be enough if you want to just make things work. But,if you want to understand why they work atleast in the superficial level, you can't do that with aurdino(i've never used aurdino but being an electronics student myself and an active IEEE member i learned from others and internet how largely it simplifies things.......) so,that concludes it scott. Do all the things possible with your aurdino board and then after getting a lot of confidence move on to some real elcetronics by checking out blogs and some sites....like circuits today,electronics for you and there are many other things for micro controllers specially. I don't have an answer for your second question right now. But,if possible i ill consult with my pals who used to work with aurdino and tell you........ Have a nice day.......