Coastal style takes its cues from beach houses — palettes of white, sand, and ocean blue; natural fibers like rattan, jute, and linen; soft, slightly worn textures; furniture that doesn't mind a damp foot. It's broader than the kitschy "Hamptons" or "Cape Cod" stereotypes — Mediterranean coastal, Australian coastal, and California coastal each have their own character within the family.
The principles are airiness and indoor-outdoor feel: large windows, sheer curtains, light-colored floors, furniture you can drop a wet swimsuit on. Pattern is minimal but present — a single striped rug, a stripe-piped pillow, a coral or shell as art rather than literal decor.
The modern version pulls back on the kitsch (no anchors, no fish nets, no "BEACH" sign on a piece of driftwood) and emphasizes texture and light. Think Belgian linen sofa, plaster walls, raw wood ceiling beams, sea grass rugs.