What are Log Files?

Log Files in a computer system are used to keep a registry of events, processes, software runs, and communication history (messages) between different users of a communication system. Executable files can also create and maintain log files to keep a track of all program-related activities.

The actual act of writing information in the log file is known as "logging". Every computing device maintains log files, including desktops, laptops, mobile phones, tablets, web servers, and much more. There are a number of different file formats used for this purpose.

Popular Log File Extensions

ETL — Format: Binary
Files with the “.ETL” extension are log files created by Microsoft Tracelog, an event tracing framework for user-mode applications and kernel-mode drivers created by Microsoft. The file itself store high-frequency events as well as track the system performance. When a trace session is run, a trace log is generated and written to a log file in a binary format to store any information related to disk access and page faults.
EVT — Format: Binary
Files with the “.EVT” extension are log files created by Windows Event Viewer, a Microsoft Windows tool responsible for storing event information which can be viewed by the computer users. An EVT file is stored in a Binary Format and contains system event logs consisting of log messages with IDs and insertions strings.

File Extension	Total Number of Files	Oldest File (Date)	Latest File (Date)
EVT	4	SecEvent.Evt (04/24/2017)	Events.evt (12/21/2019)
ETL	15978	snapshot.etl (04/11/2009)	HxCommAlwaysOnLog_Old.etl (03/30/2020)
EVM	1	SCM.EVM (11/21/2010)	SCM.EVM (04/24/2017)

What are Log Files?

Popular Log File Extensions

File Database Breakdown - Log File Extensions

Top Log File Extensions