Because most log files are recorded in plain text, the use of any text editor will do just fine to open it. By default, Windows will use Notepad to open a LOG file when you double-click on it. You almost certainly have an app already built-in or installed on your system for opening LOG files.
This post focuses on log files created by the three main operating systems--Windows, Mac, and Linux, and the main ways to access and read log files for each OS.