For SharePoint 2016
%COMMONPROGRAMFILES%\Microsoft Shared\Web Server Extensions\15\Logs
For SharePoint 2013
%COMMONPROGRAMFILES%\Microsoft Shared\Web Server Extensions\15\Logs
For SharePoint 2010
%COMMONPROGRAMFILES%\Microsoft Shared\Web Server Extensions\14\Logs
For SharePoint 2007
%COMMONPROGRAMFILES%\Microsoft Shared\Web Server Extensions\12\Logs
Note: The sharePoint Trace log path can be changed by opening Central Administration > Monitoring > Reporting > Configure Diagnostic Logs
For more details check SHAREPOINT ULS VIEWER