multiselect

A multiselect is a user interface control that allows users to select more than one option from a list or dropdown. It contrasts with a single-select control, where only one option can be chosen. Multiselect is commonly used when multiple items may be applicable at once, such as tagging, categorization, or permissions assignment.

Common implementations include a multiple-select list box, a dropdown menu that supports selecting several items, and checklists. In HTML, the select element can enable multiple selection by using the multiple attribute and optionally a size to show several items at once; many frameworks render a stylized multiselect widget. Users typically select multiple items with check marks, or by holding a modifier key (such as Ctrl or Shift) while clicking, or by tapping on touch devices. Accessibility requires clear labeling, focus management, and roles such as aria-multiselectable.

Data handling: selections are usually collected as a list or array of identifiers. When submitting forms, multiple values are serialized, often using repeated parameters or array syntax. On the server side, the selected values are processed as a collection. In APIs, multiselect fields accept arrays of values. Sorting and grouping can help users manage large option sets. Features such as “Select All” and “Clear All” improve usability, especially for long lists.

Considerations: performance and usability matter for very long lists; virtualization or search/filtering can help. On touch devices, tap targets should be large enough and feedback immediate. Designers should ensure that multiselect is accessible to assistive technologies and keyboard users.