For more than 35 years, the anonymous counterculture artist Banksy has festooned the world’s streets with his satiric and whimsical artwork skewering everything from war and weapons to pop culture and politics. But how much does the American public really know about Banksy, the street name for the artist who started out in 1990 painting graffiti around his native Bristol, England, and now sits atop an estimated $50 million global fortune? San Diegans can explore the life, work and artistic mission of Banksy beginning Friday at “The Art of Banksy: Without Limits,” an international touring exhibition in residence at the Del Mar Fairgrounds’ Activity Center through mid-April. The rats also represent his mission of speaking up for the hungry and oppressed, including immigrants, refugees and child laborers. Edison said he was impressed by the breadth of the exhibit and the many social topics the artwork addressed.