## Group and Category

At the top of the main graphical user interface you can select both a group and a category.

### Group

If you select a group (e.g. Automobile, Office, Physics, Travel, etc.), the category will be filled with appropriate entries. So the group is a kind of a filter which category in which order will appear on the graphical user interface of the program. Categories can appear in multiple groups. For example, the category called "Exchange Rates" can be found not only in the group "Travel", but also in the group "Office".
A special meaning have the entries called "All" and "Random". If you select "All", all categories become visible and if you select "Random", at least one up to seven entries are being selected to populate the category combo box.
If you select a group, a small filter symbol appear in the right lower corner of the main window. If you click on that symbol, the group will be resetted to "All" and you will see all categories again. For more information see also Groups (Filter for Categories).

### Category

If you select a category (e.g. Length, Area, Volume, Roman Numerals, etc.), both "Source" and "Target" will be filled with appropriate entries. In order to see all categories, it could become necessary to scroll in the combo box. You can also edit categories. If you have modified the list of categories, you can see the modifications immediately after you have selected "Edit / Categories / Reload categories".