.NET - do i need it?

[Mojary]

hi guys. ok so i got on the web to read up regarding .NET. i understand that there are some files that would need this. but can any of you actually explain it to me like im a little kid? ive read posts where the more knowledgeable members are advising other members to install it on their phone for some files they need. do i need to install the cab just in case in the future a file i need to install need .NET? what would be the types of files do i need to use this on/for?

any input from you guys is greatly appreciated!