Gold (#FFD700) is a very light, highly saturated yellow hue. The CSS gold keyword is a bright metallic yellow; for a realistic metallic look designers often add a gradient.
In RGB it is made of 255 red, 215 green and 0 blue. Its HSL hue angle is 51° with 100% saturation and 50% lightness, while its perceptual OKLCH lightness is 89% with a chroma of 0.182. For print, a starting CMYK mix is 0% cyan, 16% magenta, 100% yellow and 0% black.
As a text color on white, Gold has a contrast ratio of 1.4:1, which fails WCAG AA even for large text. On black it reaches 14.97:1 and passes AA for normal text. If you use Gold as a background, put black (or very dark) text on it. The APCA lightness contrast is Lc 84 for black text and Lc -22 for white text.
Its perceptual complement is #CFD8FF, close to periwinkle. Colors that look most similar are mustard, amber, lemon. It looks fairly similar to people with red-green color blindness (ΔE 2), so its meaning mostly survives.