This component provide a user interface element that lets a user specify a color, either by using a visual color picker interface or by entering the color into a text field in #rrggbb hexadecimal format.

The element's presentation may vary substantially from one browser and/or platform to another—it might be a simple textual input that automatically validates to ensure that the color information is entered in the proper format, or a platform-standard color picker, or some kind of custom color picker window. 

HTML Color Picker is very easy to use just need to take dependency of HTMLColorPicker web block from HTMLColorPicker module and it'll ask for below parameters.

It has 4 Input parameters mentioned below -

InputId* (Text)  - Input field Id on which color picker will be attached.  

DefaultValue (Text)  - DefaultValue is always a string which contains a 7-character string specifying an RGB color in hexadecimal format.