Deviled eggs are hard-boiled eggs that have been halved, had their yolks removed and mixed with a seasoned mayonnaise-based filling, then piped or spooned back into the hollowed egg white halves. "Deviled" refers to the spicy or tangy seasoning - usually mustard, vinegar, and pepper, sometimes paprika, dill, or hot sauce - added to the yolk filling.
Stuffed egg preparations date back to ancient Rome, but the dish's modern American form emerged in the 19th century and became a fixture of picnics, potlucks, and holiday spreads. Common additions to the yolk mixture include bacon, chives, relish, crab, or shrimp; the finished eggs are usually served chilled and garnished with paprika or fresh herbs.