.NET is a programming framework created by Microsoft.SOFT <coders> Bangladesh’s developers use this to create applications more easily. As commenter wroth aptly put it, “a framework is just a bunch of code that the programmer can call without having to write it explicitly.”
In a perfect world, you wouldn’t need .NET Framework. The makers of all your crucial applications would have the time and resources to fully patch together their applications into self-contained packages, because developing for Windows would be an intuitive, mostly high-level process that independent developers could nail down in fairly quick order. So nobody besides developers would need a package like .NET, which provides applications with an orderly way to access databases, web services, and other communication tools.
But you don’t live in that world, and we certainly don’t write in it. Lifehacker has often recommended applications, usually from small and independent developers, that require some version of the .NET Framework be installed to function. It’s often a big download, and sometimes prone to errors, as you’ve seen—less so in Windows 7, but any big software patch has the potential for error. BlackBerry’s need for the Framework is a bit unusual for a large-scale effort, but not entirely unheard of.
Most times, applications will ask for a particular version of the framework to be installed. We’d recommend avoiding installing that particular version, and trying instead to install the most up-to-date version of .NET, assuming your Windows OS supports it. Most .NET packages have backwards compatibility, so an app asking for the 2.0 framework can usually get by with what’s packaged into the latest version: .NET Framework 4. Be sure, too, that you’re settled up on your Windows Update requests, as there may be relevant system patches that need installing before .NET will fit comfortably on your system.