In addition, each public key you receive can have signatures attached to it. These signatures are basically other people attesting to the identity of the owner of the key. For instance, if Alice were to sign Bob's public key, then Alice is swearing that, to the best of her knowledge, the public key in his possession actually does belong to the person named Bob. By exchanging signed public keys, we create something known as a ''Web of Trust'' (described below).
This ''Web of Trust'' is used to help prove that people are who they claim to be in ways which are unique to the online community. These ideas will be explored more fully in the next section.