display controls layout. block takes full width on a new line. inline flows with text. inline-block is inline but accepts width and height. flex and grid are powerful systems for arranging groups of elements.
The display Property
display: block; /* full width, new line */
display: inline; /* flows with text */
display: inline-block; /* inline but can set w/h */
display: flex; /* flexbox container */
display: grid; /* grid container */
display: none; /* hidden (removed from layout) */
display: contents; /* removes wrapper visually */
visibility: hidden; /* hidden but keeps space */