<details>
A block that opens and closes without a line of JavaScript.
The first child is the <summary>, which becomes the trigger; the rest of the content appears when the open attribute is present. The browser handles the click, the keyboard, focus and state. In Chromium-based browsers, the page's own find-in-page can open a closed <details> to show what it found.
The name attribute turns several sibling <details> into a single-open accordion — behaviour that needed script until the day before yesterday.
<details name="gaveta">
<summary>Label and rarity</summary>
<p>Forms · forgotten</p>
</details>
<details name="gaveta">
<summary>Notable attributes</summary>
<p>value, min, max, low, high, optimum</p>
</details>Label and rarity
Interactive · common
Notable attributes
open and name
Where it was collected
HTML Living Standard, among the interactive elements.