It’s referenced in the 1x1 gif, all website layout was made with tables. And the 1x1 gif allowed to set very narrow columns/rows, which could be made to look like borders, with images as the round corners.

Also the ubiquitous visitor counter, uploading assets with ftp, cgi-bin, styling in html, animated gifs, midi soundtracks, “in construction” signs, random links to pages the “webmaster” liked.