SalesForce is the first true cloud system in CRM, it is multi tenant cloud platform, 100s and 1000s of companies shares tenant but data is isolated from other Organizations.

The meta data in SalesForce hold all the data realted to the org such as flows, workflows, ui everything related to the Org is one set.

SalesForce is for Large enterprise customers it is one of the most complex systems in CRM given the fact it has its own programming language, APEX.

SalesForce can be signed in at SalesForce Developer Login

Good concepts in Microsoft Technology such as ASP.NET concepts JavaScript will certainly help understand SalesForce.