If we are working with Visual Studio and Solution Explorer contains multiple projects, it becomes very difficult to focus on the particular projects. Visual Studio 2012 and later versions provide the "Scope To This" option. Using this option, we can select any project and then only this project will be visible in Solution Explorer. You can select a particular project or a folder from Solution Explorer.
To activate this option right click on any project or folder and select "Scope To This" option.
Now, you will find that only the selected project or the folder is visible in Solution Explorer.
To come back to the the original state, just click the "back arrow", visible at the right top corner.