The avg file extension is related to AVG Antivirus software from the Czech company AVG Technologies (formerly Grisoft).
The avg file contains virus database used to update the definitions. Might have been used in older versions of the program.
How to open:
The avg files are used for internal purposes of AVG Antivirus.
How to convert:
As far as we know, this .avg file type can't be converted to any other file format. This is usually the case of system, configuration, temporary, or data files containing data exclusive to only one software and used for its own purposes. Also some proprietary or closed file formats cannot be converted to more common file types in order to protect the intellectual property of the developer, which is for example the case of some DRM-protected multimedia files.