A colour gamut is a subset of colours, such as those in a specific colour space.
The range of colours printers, cameras, scanners, monitors etc. can reproduce varies, so a colour gamut is used to make these differences clear and it also shows what colours these devices have in common.
sRGB, Adobe RGB and NTSC all have their own colour gamut which is often shown on what's called an xy chromaticity diagram. This diagram was established by the International Commission on Illumination (CIE) and the colours of the visible range are represented using numerical figures and graphed as color coordinates.
In the diagram here, the large shape surrounded by a dotted line represents the range of colours visible to the human eye. The color gamut defined by each standard (sRGB, Adobe sRGB and NTSC) are shown as triangles on the diagram. These triangles show the peak RGB coordinates connected by straight lines.
The larger the area of the triangle, the more colours can be displayed. For LCD monitors, this means that one which is compatible with a colour gamut that has a larger triangle will be able to produce a wider range of colours on screen.
The colour gamut of an LCD monitor's hardware can be indicated using similar triangles. An LCD monitor can't reproduce colours outside its color gamut.
Calibration And Colour Gamut
To make full use of an LCD monitor with a wide colour gamut and to display colors as the user intended it's important to maintain a colour calibration system. For more tips on colour calibration, take a look at EIZO ColorZone's technique section.