Steam uses BLOB files to store user data. BLOB stands for Binary Large Object. These files hold multimedia data like images and video.
The ClientRegistry.blob file stores user information for the Steam software. The AppUpdateStats.blob file stores application update data. Steam was created by Valve Corporation to distribute games online.
If Steam cannot open a BLOB file, installing the latest Steam version may help. Also associate BLOB files with Steam. If that does not work, manually delete the problem BLOB file with Steam closed. Steam will recreate the file when restarted.
The BLOB file extension is mainly used by Steam on Windows and Mac operating systems. Some other software can also create BLOB files for different purposes. Generic blob data files often use the .BLB extension instead.
Microsoft SQL Server
MySQL
Oracle Database