According to National Geographic’s Color Palette guidelines, yellow is the primary brand color and should be used for most accents or calls to action. “Tints are also available but should be used rarely, such as for background color fields, showing data in a graduated way, or as hover states.” The yellow establishes National Geographic’s brand, and makes the layouts easily recognizable as belonging to Nat Geo. The yellow bar used at section fronts also helps establish hierarchy and to separate the section headers from the rest of the text. The other yellow accents are spread sparsely throughout the magazine, so that the publication can use the same shade of yellow for every issue without becoming boring—the yellow accents create consistency, without overdoing it.
Neutral grays are used mainly for type elements, background color fields, and borders.
Black is used for body copy and for captions placed on light photos or in white borders around a dark photo. This sophisticated approach is legible, classy, and simple.
White is used for captions on dark photos, or in articles over neutral gray/black boxes over images. This way, the designer can fill an entire page or spread with an image, while still providing the text needed. 
Green and red swatches are provided for affirmation and warning use cases, such as calls to action or alerts. Because these colors are used so rarely, they stick out to the reader, making the element’s importance evident.
Social icons are displayed in their native brand colors, making calls to social media easily recognizable by the reader.
