Magic Wand / Select Color Range
In contrast to the selection tools described above, the magic wand selects pixels according to their color. Contiguous pixels that are similar in color to the pixel you clicked will be selected.
This tool is the same as the magic wand except the selection is not restricted to contiguous pixels.
Active Tool manager options
If this option is enabled, the selection will be based on the composite image of all visible layers. With the option disabled, the selection will be based on the active layer only.
The Tolerance value defines how similar contiguous pixels must be in color compared with the pixel you clicked in order to be selected. You can set values from 0% to 100%.
If you set Tolerance to 0%, only pixels of identical RGB color to the pixel you clicked will be selected.
With a Tolerance of 100%, all pixels will be selected.