The horizontal lockup is the primary form. Use the stacked lockup where the space is squarer than it is wide, and the icon alone only where the name is already present.
For favicons, app icons, and avatars. Holds to 32 px in full color, 24 px in single ink.
Favicons. The SVG scales to every size and is what most browsers use. PNGs are provided for iOS home screens and web app manifests.
The default. It needs white or a very light ground to hold its edges.
The full palette with a white ring and wordmark. For ink grounds, dark photography, and the footer of a dark page.
One-color printing, embroidery, engraving, and any ground too busy for six colors. A genuinely single-color file.
On ink, on photography, and on any of the six colors. Never place it on a light ground.