Hi,
1-What is bandewidth ?
2-How to calculate ?
3-How to measure ? Any free software to measure it ?
Many thanks.
To answer this question I would have to write a book. Could you please be a bit more specific?
Darwin
you are allright 
very simple Sir,
it has a definition ? What is it ? You do not need to write a book for this.
You can measure it. How ? Any free software to measure it ? The answer is the name of a software and not the content of your book.
Regards.