This tool is an online color picker. The big colored cross is one of the eleven possible shapes of the deployed surface of the RGB cube, which is the three-dimensional space formed by combinations of red, green, and blue.
Select a color in the cross by clicking on it and a set of shades of that color will appear at the right hand side extreme. You can select any of those shades by clicking on it.
Once you have chosen a color, you can select either the Hex or the RGB code of that color by clicking once on their respective text areas. Then you can copy any of those codes to your computer memory in order to paste them later.
If you click again on the last square you selected in the cross, the selection will be undone.
To save a color click on the “Save color” button. This button, located below the cross, is only available when you have selected a color and there is an empty space to save it. To remove a saved color hover your mouse over that color and then click on the X at its top right hand corner.
In order to share your saved colors with someone, or just to see them later, this tool provides a link that you can copy and paste. The text area with that link is right below the space for the four saved colors.
Tools >> Color Picker