A character limit is the maximum number of characters that a platform or system allows for text input. X (Twitter) allows 280 characters, Instagram captions allow 2,200, and Google Ads headlines allow 30. Each service has its own limits.

Character limits serve multiple purposes: optimizing user experience, ensuring database efficiency, and maintaining consistent display layouts. Social media marketing books discuss strategies for maximizing impact within character limits.

How full-width and half-width characters are counted varies by platform. X counts both as 1 character, while some systems count full-width as 2.

Writing effectively within character limits requires prioritizing information and using compression techniques. Copywriting fundamentals books teach character-conscious writing skills.