1. CSS Logical Properties

    Logical properties and values provide control of layout through logical, rather than physical, direction and dimension mappings. These properties are `writing-mode` relative equivalents of their corresponding physical properties.

  2. HTTP/2 protocol

    Networking protocol for low-latency transport of content over the web. Originally started out from the SPDY protocol, now standardized as HTTP version 2.

  3. Selection controls for input & textarea

    Controls for setting and getting text selection via `setSelectionRange()` and the `selectionStart` & `selectionEnd` properties.

  4. Lazy loading via attribute for images & iframes

    The `loading` attribute on images & iframes gives authors control over when the browser should start loading the resource.

  5. Lazy loading via attribute for video & audio

    The `loading` attribute on video & audio elements gives authors control over when the browser should start loading the media resource, allowing deferred loading until the element is near the viewport.

  6. Server Name Indication

    An extension to the TLS computer networking protocol by which a client indicates which hostname it is attempting to connect to at the start of the handshaking process.

  7. console api: `timestamp()` static method: `start` parameter

  8. eventtarget api: addeventlistener: form with `options` object supported (third parameter can be either options or a `boolean`, for backwards compatibility): `options.passive` parameter defaults to `true` for `touchstart` and `touchmove` events

  9. htmlolistelement api: start

  10. range api: collapse: `tostart` parameter is optional

  11. selection api: collapsetostart

  12. css property: border-block-start-color

  13. css property: border-block-start-color: currentcolor

  14. css property: border-block-start-color: transparent

  15. css property: border-block-start-style: solid

  16. css property: border-block-start: currentcolor

  17. css property: border-block-start: solid

  18. css property: border-inline-start-color

  19. css property: border-inline-start-color: currentcolor

  20. css property: border-inline-start-color: transparent

  21. css property: border-inline-start-style: solid

  22. css property: border-inline-start: currentcolor

  23. css property: border-inline-start: solid

  24. css property: column-rule-inset-cap-start

  25. css property: column-rule-inset-cap-start: overlap-join

  26. css property: column-rule-inset-junction-start

  27. css property: column-rule-inset-junction-start: overlap-join

  28. css property: column-rule-inset-start

  29. css property: column-rule-inset-start: overlap-join

  30. css property: grid-column-start

  31. css property: grid-column-start: auto

  32. css property: scroll-margin-block-start

  33. css property: scroll-margin-inline-start

  34. css property: scroll-padding-block-start

  35. css property: scroll-padding-block-start: auto

  36. css property: scroll-padding-inline-start

  37. css property: scroll-padding-inline-start: auto

  38. css property: scroll-snap-align: start

  39. css selector: `::scroll-button()`: block-start

  40. css selector: `::scroll-button()`: inline-start

  41. html element: ol: start