Why do you think Microsoft has emerged as a global leader in software industry?

All their products are more user friendly....

Billgates concentrates more on asian markets, Where he can sold out his products in large number...

Because they have launched most robust products and most selling, popular products all over the world. Thats why they are global leaders.

microsoft develop most useful and user friendly softwares

Microsoft is popular because 1->it provides the facilities to user point of view ,i.e,there is no problem regarding coaching to use these software ,you can use them without any type of special skills.In other words these software are user friendly.

2->due to functionality of the software

I challenge your assertion that MS is a Global leader, especially since the emergence of open-source platforms and software such as Linux, android, eclipse, java and php.

Yes, MS is one of the important Global Players, and is to be credited with several innovations in the software industry such as the .NET Framework with Garbage collection and JIT (Just-in-time compilation), and also its comprehensive focus on usability and RAD Tools.