e-commerce in broad defined definition is the environment or market place using electronic network doing commerce, i-commerce (internet commerce) may use to replace narrow defined definition of e-commerce(only refer to selling and buying in electronic stores on the net.)
In fact, some people talk about e-commerce is refered to narrow defined definition ( selling and buying in electronic stores on the net . ) ,
e-business is the broad definition of business that rely on electronic network in some or in all of their business processes,

In 1999, the amount of e-commerce in USA is US$507 billion, rise 68% of 1998 amount US$301 billion
the amount of i-commerce(selling and buying in electronic stores on the net.) is US$108 billion, rise 68% of 1998 amount (US$64 billion)
( data based & refer to report of University of Texas http://crec.bus.utexas.edu)

As the amount of e-commerce continue to grow in last few year all over the world, there are a micro-economic system formed by e-commerce.
e-commerce in some aspect stand for 'True globalization of business & labour'.

In fact, we need systems different from tradition system in "Legal framework, Taxation system, Monetary and fiscal issues and .... " for e-commerce.
The development of e-commerce is unlimited all over the world in near few year.