There are more than 140 States and non-state entities (e.g. United Nations, European Union) currently issuing ePassports, and over 1 billion ePassports in circulation. ePassports add a layer of security to traditional non‑electronic passports by embedding an electronic chip in the passport booklet that stores the biographical information visible on page 2 of the passport, as well as a digital security feature. This digital security feature is a country specific "digital signature." These digital signatures are unique and can be verified using their respective certificates.