Can someone explain the PHP concept in blog posts for showing text until read more is inserted and some function which can recognize the read more tag like in wordpress <!--more--> and show text until tag read more is inserted. Thanks
You can just use a string split around the read more tags, anything before it is essentially your abstract, the concatenation of the before and after is your full text.
You can use javascript on the frontend to switch between the abstract and full text when pressing the more/less buttons.