With filtering you limit the number of displayed images in your current collection (see also Section 2.3.2, “Collect images”). Filtering is mainly based on the star ratings of your images. A typical filtering rule will show all images that have a rating at or above the given number of stars (from one to five). The comparison operators is not restricted to “≥”. By clicking on the operator field you toggle between “≥”, “>”, “≠”, “<”, “≤”, and “=”.
Alternatively you can make darktable display “all” images, only the “unstarred” ones, only the “rejected” images and all but the rejected ones.
Images in the lighttable view can be displayed in different sort orders, depending on “filename”, “time” (when the photo was taken), “rating” (i.e. stars), “id” (an internal ordering number of darktable), “color labels”, “groups”, “full path”, “title”, “description”, “aspect ratio” or “custom order” (user can drag & drop images, only available in the lighttable's file manager mode). You can sort in reversed order by toggling the triangle button to the right of the “sort by” combobox.
When “tag” is at the first level of Collect module, the images order is saved along with the selected tag. As a tag can be seen as a collection of images, it is then possible to associate to every collection (or tag) a specific images order, including a “custom order”.