Flash of unstyled content

Flash of unstyled content (FOUC) refers to the phenomenon when a user intends to consume a "modernly-styled" webpage but encounters a page with:

• only black text on white background
• images that appear raw and unsized (usually oversized)
• an absence of layout (everything appears stacked)

The temporary lack of style on the webpage happens for only a second before the style restores. This occurs because the HTML (structure and content) has already loaded, but the CSS (styling) file has not fully loaded yet. It most commonly happens on slow internet connections. However, improperly programmed websites may still have FOUC on faster connections.