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+Since PGPainless is based on Bouncycastle, it follows some of the terminology introduced by Bouncycastle. That might be confusing for new users, especially for users coming from GnuPG.
+
+## Keys, KeyRings, KeyRingCollections
+
+What is considered a KeyRing in GnuPG (a collection of keys) is called a KeyRingCollection in Bouncycastle/PGPainless.
+Similarly a Key in GnuPG is called a KeyRing in BC/PGPainless. This is due to the fact, that an OpenPGP key can actually consist of more than one key (master - subkey structures). A Key in BC/PGPainless is either a master key or a sub key.
+
+| PGPainless Term   | GnuPG Term     | Description                                                              |
+|-------------------|----------------|--------------------------------------------------------------------------|
+| KeyRingCollection | KeyRing/KeyBox | Collection of OpenPGP keys (either of a single user or of multiple users |
+| KeyRing           | Key            | Master key which might have sub keys                                     |
+| Key               |                | Single key which might be a master key or a sub key                      |
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