There is also another approach of mapping density, called binning. Generally speaking, binning is a technique of grouping N values/features into M groups, where M < N. The result of such an operation can be interpreted as a two-dimensional histogram.
Binning is an alternative to heat maps, not a replacement. The choice of the method depends on the requirements and further usage of the results. It is, however, worth mentioning that binning produces a vector output, while a heat map produces a raster output.
In general, binning can be described in two simple steps:
Create a hexagonal grid on top of the point layer.
Count the number of points in each grid cell.
In this section, you will learn how to use this technique in QGIS in the example of hexbinning, in other words, mapping density with a hexagonal grid.