Is LocalDB installed independently of SQL Server? I am a Developer.  I thought LocalDB was installed as a component of Visual Studio, which could be used for development purposes.  However, it appears to be installed independently of Visual Studio.

Is it installed as part of SQL Server; SQL Data Tools or both?
LocalDB is an optional feature of SQL Server Express edition.  It may be installed by:

1) Selecting the LocalDB feature during installation of SQL Server Express 

2) Selecting the .NET desktop development feature during installation of VS 2017. According to this thread, SSDT does not automatically install LocalDB.