OS X comes with a built-in Summary Service app that summarizes long text into shorter form, essentially producing a TLDR! (Too Long Don’t Read) version of the text. The app is rather hidden and is not found under the usual Applications folder. Rather it is intended to be used as an OS X service.
Summary Service is not turn on by default. To set it up, go to System Preferences > Keyboard on the Mac.
Click on Shortcuts section then select Services on the left pane. Scroll down to search for “Summarize” on the right pane and check to switch it on.
Once the Summary Service is turn on, you can access it via the contextual menu whenever a block of text is selected for example from a web page, Notes app or Pages documents.
You right-click to bring up the contextual menu once text is selected. From the menu, select Services > Summarize to launch the Summary Service app.
The selected text will appear in the main window of Summary Service app. To make a shorter version of the text, drag the “Summary Size” slider.
By default the summary size is at 100% which means there is no changes made to the original text. Drag it to a lower percentage and see how the app summaries the text.