Configuring Audit Logs Feature in SharePoint 2013

Audit log reports in SharePoint used to track how your SharePoint site contents are being used or to meet any legal compliance requirements. Lets see how to enable auditing feature in SharePoint 2013.

Enable Audit Log Feature in Central Administration:
SharePoint 2013 audit settings needs to be enabled starting from Central Administration site.

• From SharePoint 2013 Central Administration: Under Application Management, Click on Manage service applications.
• Select "Secure Store Service application", and click on "Properties" from the ribbon.
• Scroll down and Enable Audit section, and select the Audit log enabled box. Set the number of days to keep audit logs until purged.
• Click OK to save your changes.

Enable Auditing Feature at Site collection level

• Go to your top level sites settings page (Site collection settings) 
• Click on "Site collection audit settings" link under Site Collection Administration. 
• In configure auditing page, enable relevant events such as "Editing Items", "Deleting or Restoring Items" check boxes
• Once done, Click on "OK" to save your changes.

To View Audit Log Reports
When audit functionally is enabled, All selected events on SharePoint site content will be automatically logged. Then we can filter and analyze the audit data for sites, lists & libraries, content types, list items (documents) in the site collection. To view Auditing reports, head on to:

• Site Settings of the Root web
• Click on Audit log reports under site collection Administration
• Pick the relevant report. You can choose custom report as well.

You can enable auditing on: site collection, library/list, folder, content type levels.

Enable Auditing at Library/List Level:

• Go to your library >> Library Settings >> Under "Permissions and Management" click on "Information management policy settings"
• Under the Content Types, Click on the relevant content type to enable auditing on the particular item (E.g. Documents)
• Scroll down to Auditing section and choose  the events you want to add to the audit log

Trim Audit Log in SharePoint 2013:
Although auditing is a nifty feature in SharePoint, enabling auditing for a site where large number of events takes place, may result with large audit logs which can affect the overall performance of the SharePoint farm. So, It's recommended to enable audit log trimming for site collections.
Related post: How to Trim audit log to Improve Performance in SharePoint