Text selection is the highlighting that appears when someone marks words on a screen. It is like placing a transparent colored strip over a sentence in a book.
People select text to copy it, search for it, or make an edit. A website can choose the highlight color, but the marked words should remain readable.
Avoid preventing selection of ordinary text without a strong reason. People may need to copy an address, quote, or error message, and blocking that simple action can make the page frustrating.