Categories as a perfect to filtering your markers and allowing your visitors to show only certain types of markers. Visitors select the category via the drop down field.
How to create Marker Category
Step 1 Go to Add Marker category from WP Google Map Plugin.
Step 2 Choose parent category (optional),and enter Title of your category.
Step 3 Assign a icon to your marker. You can change icon using Choose button.
Step 4 Then Click Save Marker Categor button. All the categories that you created are displayed Marker categories Page.