Facets are used for grouping documents based on criteria, such as specific terms or a date range. 

Range facets group documents based on ranges into which a numeric or `DateTime` field falls. Unlike [Histogram facets](🔗), the ranges need not be an interval, such as 0-10, 10-20. Instead, they can be different sizes and overlap each other, such as 0-10, 5-20. Also, unlike histogram facets, range facets return more than just the number of documents in each range, such as minimum, maximum, and mean values.

To request range facets, use the `RangeFacetFor` method. Its first parameter is an expression, which you use to select the property to group documents. The second parameter is an array (params) of `NumericRange` or `DateRange` objects, depending on the first parameter's property type. Numeric or `DateTime` field range types have two properties, named From and To, of type nullable double and nullable `DateTime`, respectively.

After executing a search request with range facets, you retrieve facets from the result object using the `RangeFacetFor` method (the same name used to request them). This method has one parameter, an expression saying what property the range facet is for.

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Note

Ranges are inclusive for the lower bound and exclusive for the upper bound. That is, a range from 0 to 10 matches 0 but not 10. The same goes for date ranges, where a range from 2012-01-01 to 2012-01-31 matches 2012-01-01 but not 2012-01-31.

The following example groups products into three price ranges.

In the above example, you create several ranges and request a range facet for products falling into those ranges. In the first range, you do not specify the `From` property, effectively saying that the range is for products with a price below 100. Similarly, the third range does not specify the `To` property, requesting products that cost 300 or more.

Upon retrieving the search result, you can retrieve and inspect the facet. Below is an example of this: writing information about each range to the console.

The above code produces output like this:

Range to 100 Count: 61 Min: 0,5 Max: 97,3 Mean: 42,3237045467812 Total: 2581,74597735365

Range from 100 to 300 Count: 52 Min: 100,0 Max: 299,0 Mean: 205,738167025743 Total: 10698,3846853387

Range from 300 Count: 51 Min: 301,5 Max: 942,8 Mean: 566,562194859469 Total: 28894,6719378329