Expansion Panel builds independent collapsible sections with a header and body. Use ngs-expansion-panel for one section, and wrap panels in ngs-accordion when a group should coordinate single or multiple open panels.
Use it for settings groups, FAQs, advanced options, filters, grouped form sections, detail sections, onboarding or setup steps, and inspector groups. Do not use it to truncate one long text block, render a tree, build tabs, force a strict stepper flow, or as a plain card/container without collapse behavior.