Family Araneidae - Orb weavers
Genus Argiope includes large garden spiders that sit in the center of their webs and often have a stablimentum in their web.
This spider goes by many names: Golden Orb-weaver, Yellow Garden Orbweaver, Writing Spider, Black & Yellow Argiope.
This is a fairly large spider and one of my favorites.
All images © Kim Moore (contact for use)