If you're working with a database created in a previous version of Access, you can convert it to the 2007/2016 file format to take advantage of the new features. You can also convert from the Access 2016 format to older versions of Access.
An Access 2016 file (.accdb) can only be opened in Access 2007/2016 and not earlier versions of Access so make sure everyone who uses the file is running the correct version before you convert it.
If you have any open database objects, you'll see a message telling you to close them. Click Yes. If Access is unable to convert the file, you'll also see that message at this point.