The file extension SLN is used by Microsoft's Visual Studio products. (eg Visual Studio 2010 Express) A SLN file is a Visual Studio Solution file and contains information about one or more projects.
Microsoft Visual Studio is a so-called IDE (Integrated Development Environment), ie integrated development environment and for various programming languages (C-Sharp, C ++, Visual Basic) available.
The SLN file is used to organize projects and project components. Since such a file contains only references and some settings data, you always need the project folder and the project file. This varies depending on the programming language used and can, for example, call .Csproj (for a C # project)
SLN files are indirectly downwards compatible. Visual Studio automatically detects and converts SLN files saved with older Visual Studio versions, making the whole project usable.
Unfortunately, the SLN file does not recognize the programming language used by the project. The only remedy here is the extension of the project file or a look into the project folder. Depending on the programming language used, you will find vb, c, cpp, or cs files there. To open a SLN file, Visual Studio must also be installed for the appropriate programming language.