Circoviridae is a family of small, circular DNA viruses that primarily infect birds and pigs. These viruses are known for their stable structure and can cause various diseases in their hosts, including respiratory and reproductive issues. The family includes notable members like Porcine circovirus (PCV), which is associated with several pig diseases, and Avian circovirus, affecting birds. Circoviruses are typically transmitted through direct contact or contaminated environments, making biosecurity important in managing their spread in livestock and poultry.