Let's keep in mind that Provence is not a perfectly delimited geographical entity, but rather the reminder of a Roman era and the first Gaul conquest, named Provincia, which inspired today's designation of Provence.
Thus Provence covers all the different parts of southern France. Using today's administrative borders as guidelines, these include the departments of the Alpes-de-Haute-Provence, Bouches-du-Rhône, Var, Vaucluse (the Avignon region only), a part of the Alpes-Maritimes (to Nice) and, let's not forget that small area called Drôme provençale, in the Rhône-Alpes region.
Above and beyond being a territory, Provence is more precisely an identity, one whose common vector was, for a long time, the Provençal dialect.
In the Northeast, the Drôme provençale is the gateway to Provence, with Montélimar its most representative city. It is the ideal location from which to tour the area, being of equal distance to Lyon, Marseille, Grenoble and Montpellier.
Slightly further south, Avignon and the Comtat Venaissin (Cavaillon, Carpentras, Vaison-la-Romaine) recall the lengthy papal authority that once reigned on this land.
Along the coast, Provence stretches from the Regional Nature Park of Camargue to Nice, via Marseille, Toulon, Saint-Tropez and Cannes.
Finally, the Provençal identity is also defined by its cuisine, as is the case for many French regions. Fish-based along the coast (bouillabaisse, aïoli...), and focused on vegetables and meat higher up (daube, raviolis, pistou soup...), meals in Provence are often accompanied by local wines. The region is also specialised in sweet delicacies -- you must try the croquant biscuits and experience the 13 desserts at Christmas.