Grid systems -- invisible columns and rows that elements snap to -- are the backbone of professional layout; most design software (Figma, Canva, Adobe tools) includes grid and guide features to make alignment effortless. The principle of proximity states that related items should be placed close together and unrelated items should have clear separation, which is why a caption sitting right under its image reads naturally while one floating far away confuses the viewer. Alignment means every element should line up with something else on the page -- left edges, centers, or baselines -- because unaligned elements make a design feel accidental and unprofessional even if the viewer can't say exactly why. Symmetrical layouts feel formal and stable (good for certificates or corporate reports), while asymmetrical layouts feel dynamic and modern (good for social media and marketing), and the rule-of-thirds -- dividing a canvas into a 3x3 grid and placing key elements along those lines -- is a quick way to create natural visual interest.