By distribution is meant providing your app to others who are not developers on your team. There are two kinds of distribution:
The Portal imposes a registration limit of 100 devices per year per developer (not per app), which limits your number of Ad Hoc testers. Your own devices used for development are counted against this limit.
In order to perform any kind of distribution, you will need a distribution certificate, which is different from the development certificate discussed earlier in this chapter. Like the development certificate, you need only one distribution certificate; it identifies you as you. Obtaining a distribution certificate is exactly like obtaining a development certificate, except that, at the iOS Provisioning Portal, under Certificates, you use the Distribution tab instead of the Development tab. (And, like the development certificate, it expires when your year of iOS Developer Program membership expires; if you renew, you’ll have to revoke your distribution certificate at the Portal, delete it from your keychain, and obtain a new distribution certificate.)
You will also need a distribution profile specifically for this app, which is ...