A website wireframe, also known as a page schematic or screen blueprint, is a visual guide that represents the skeletal framework of a website.

Website wireframeWikipedia
Articles on WireframesUX Magazine
Wireframe ShowcaseWireframe Showcase
A Comprehensive Guide To Wireframing And PrototypingSmashing MagazineMarch 1st, 2018
Wireframing – The Perfectionist's GuideSmashing MagazineNovember 22nd, 2016
A Beginner's Guide to WireframingEnvato Tuts+June 18th, 2012