placeholders

A placeholder is a symbol, word, or string that marks a position to be filled with actual content later. Placeholders are used in writing, computation, and user interfaces to indicate where data will go or to reserve space in a structure.

In publishing and design, placeholder text or images stand in for final content during layout. Lorem ipsum is a famous example of filler text; placeholder images are simple gray blocks with dimensions. These help designers assess typography and spacing without relying on finished assets.

In programming and templating, placeholders are tokens substituted at runtime with concrete values. Examples include format specifiers such as %s and {} in strings, or named placeholders like {name} in templates. In SQL, prepared statements use placeholders (?, $1) to bind parameters securely.

In user interfaces, the placeholder attribute in input fields shows example text before the user enters data. It differs from a label and should not be used in place of one; placeholders can cause accessibility issues because they may disappear and be unreadable by screen readers.

Localization and data generation also use placeholders to insert values such as dates or names into strings, requiring careful handling to preserve grammar and pluralization when translated.

Best practices include using placeholders for content that will be provided later, ensuring they are distinguishable from actual content, avoiding overuse, and ensuring accessibility with proper labels and ARIA attributes.