A balanced mix between black and white, the two opposites, doesn't grant gray neither of their annotations, but rather make it a get to the middle ground and become a neutral.
Gray isn't showing extreme optimism like white, nor it is showing pessimism like black. It sits in middle with a great suggestion of practicality, seriousness and disinterest in conflicts.
How the color is made: gray is obviously made by mixing black and white with equal proportions, in RGB such colorlessness is achieved by neutralizing all components to have the same value and in the case of gray it is 128/255 (~50% of the color component). In CMYK it is made with only black (50% of it) as the other 50% is assuming the color of the paper is white.
History: gray was been used for a long time, and the first recorded use of gray was ~700 AD. And it can be seen in paintings of cloudy skies.
Occurence: In modern times, and due to its sophistication and tolerability, it is widely used in many media from UI design to interior, exterior and rural design.
Color in Action
Gray seems dull, but thinking about its connotations, gives you another chance to rethink in terms of its neutrality, boldness, practicality, and conflict-resolving nature. Also, lacking color make it very suitable with almost any other color in the visible spectrum, you don't need to think about its balance rather make sure to mind other colors balance. Gray have a certain weight if paired with white or black which create a good amount of contrast between both of them.
Colors that go with Grey
As discussed earlier, any color can go well with gray, just make sure other colors are well-balanced. It is also good to know that gray seems darker with light colors and lighter with dark colors which is a good combination of characteristics that substitute its lack of color.
Grey Color Palettes and Schemes
Any color is a good match with gray, and it can be used as a base color instead of whites and blacks. For example, to create a metallic color palette that contains gray, you might use silver, gunmetal, and any other metallic color alongside gray as a base color, and you'll end up having a great color palette.
Backgrounds and Seamless Patterns
Unlike its versatility with colors, gray is only good with geometric patterns that contains a lot of lines, also it is good with cloudy patterns, other wise the pattern will seem very soulless and dull. And we all knew that gray is good as a background color, and it is also widely used as such in dark themes in UIs. Wallpapers with gray as the base color can seem dull, but with proper execution of color balance can create astonishing wallpapers.