Power BI Audit Logs - Why do we see ".pbix" files?

[vaish9207]

We have extracted Power BI Audit Logs from web api. 

On these logs, we see that there is ".pbix" names coming in the dashboard name. 

Can you explain why ".pbix" file names come in web api data.
I thought that the data extracted from API is only data that is present on app.powerbi.com. 
What is the significance of these ".pbix" files being present in the logs. Also, there are few operations that happen like "View Dashboard", "Import", "Delete Dashboard" etc.  
I am working to create an analysis for the inactive dasboards. I am unsure if these has to be included or not included in my analysis.
Would like to understand and get more details wrt to it.

Thanks in advance.

[lbendlin]

In your words, what is the difference between a dashboard, a report and a dataset?  

Microsoft will not stop you from naming your artefacts that way.  So your report name can be "Report.pbix"  but the actual file name is Report.pbix.pbix".

[vaish9207]

@lbendlin - please help me if you have any suggestions. 

@v-yuezhe-msft - Please help with this query.