Where a catalogue answers "what does this product look like", a lookbook answers "who is this brand this season". It is built outfit by outfit, with styling, setting and casting chosen for the story. Brands send it to press, stockists and wholesale buyers, and use the images on the homepage and in social posts.
Also written "look book", it is one of the most expensive shoots a brand commissions: a location, a creative director, a stylist, models and travel, for images that have to land on launch day. Smaller labels often skip it and launch with product shots alone.