Flex the width of your viewport to see the difference in behavior between a chunked container and a fully-fluid container. A chunked container will only expand to fit the maximum width of a breakpoint. A fluid container will flex to fill all available width of a the viewport.
A "chunked" row.
A fluid row.
<768 — Extra small devices, phones
≥768 — Small devices, tables (portrait)
≥992 — Medium devices, desktops, tablets (landscape)
≥1200 — Desktops