The general available release of SQL Server Management Studio 2016 is free. No SQL Server license is required to install and use it for either development or production purposes. This GA version supports SQL Server versions 2008 through 2016 plus Azure SQL Database. You might be able to use it against earlier SQL versions too but that’s not officially supported and features will be limited. SSMS 2016, now based on the Visual Studio 2015 isolated shell, can be downloaded from the SSMS Download Page.
Prior to SQL Server 2016, one typically installed SSMS from the SQL Server installation media and was upgraded only by CUs, service packs, or SQL Server version upgrades. This changed with the release of SQL Server 2016; SSMS is a now a separate download. After installation, regular updates are made available (monthly) and can be installed from the SSMS Tools–>Check for Updates… menu option. These frequent updates allow the tooling to stay aligned with both on-prem and Azure SQL Database while delivering enhancements and bug fixes to SSMS much more quickly. I am quite impressed by the responsiveness of the SSMS development team in this regard, having used it since the initial preview versions of the VS 2015 isolated shell were made available.
An important change in this GA version compared to earlier versions of SSMS is that SET XACT_ABORT ON is now the default session setting. That’s a good thing, in my opinion, because it helps ensure one doesn’t accidentally leave a transaction open in a query window following an error (I have many horror stories about that). But it does change script execution behavior because queries, with or without error handling, will generally not continue after an error with XACT_ABORT ON. Be aware of this when running scripts from SSMS. This and other SET options can be specified from the SSMS Query–>Query options–>Execution–>Advanced. I strongly recommend specifying SET XAT_ABORT ON unless you have a specific reason not to do so.
Kudos to the Microsoft for providing SSMS as a free tool and to the SSMS development team for their ongoing commitment to SQL Server tooling improvements and timely delivery.