Use Your Mac’s Built-in Summarize Feature to Shorten Long Blocks of Text
If you have a lot of text files on your computer, it can be difficult to distinguish between them. On How-To Geek, they remind us of an often-forgotten OS X feature called Summarize.
As the name suggests, Summarize sums up a block of text. However, you need to enable this feature first. Go to System Preferences> Keyboard> Shortcuts, select the Services option and find Summarize. Check the box to enable it. Now go to the text editor of your choice, select the block of text, then right-click and choose Services> Summarize. You will see a popup where you can move the slider back and forth to resize the summary. From here, you can save the summary as a new piece of text, or better yet, copy and paste the summary into the comment section of the document itself so you can easily distinguish it later.
How to get a summary of long documents in macOS with one click | How-To Geek