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      <h1>Glossary <a href="#glossary" name="glossary" class="anchor">#</a></h1>

      <a name="advertised-bandwidth"></a>
      <p><b><a href="#advertised-bandwidth">advertised bandwidth:</a></b> the
      volume of traffic, both incoming and outgoing, that a
      <a href="#relay">relay</a> is willing to sustain, as configured by the
      operator and claimed to be observed from recent data transfers.</p>
      
      <a name="bandwidth-history"></a>
      <p><b><a href="#bandwidth-history">bandwidth history:</a></b> the volume
      of incoming and/or outgoing traffic that a <a href="#relay">relay</a>
      claims to have handled on behalf of <a href="#client">clients</a>.</p>
      
      <a name="bridge"></a>
      <p><b><a href="#bridge">bridge:</a></b> a <a href="#relay">relay</a> whose
      existence is non-public and which can therefore provide access for blocked
      <a href="#client">clients</a>, often in combination with
      <a href="#pluggable-transport">pluggable transports</a>, which registers
      itself with the <a href="#bridge-authority">bridge authority</a>.</p>
      
      <a name="bridge-authority"></a>
      <p><b><a href="#bridge-authority">bridge authority:</a></b> a
      special-purpose <a href="#relay">relay</a> that maintains a list of
      bridges as input for external bridge distribution mechanisms (for example,
      <a href="https://bridges.torproject.org/">BridgeDB</a>).</p>
      
      <a name="circuit"></a>
      <p><b><a href="#circuit">circuit:</a></b> a path through the Tor network
      built by <a href="#client">clients</a> consisting of at most one
      <a href="#bridge">bridge</a> and at least one
      <a href="#relay">relay</a>.</p>
      
      <a name="client"></a>
      <p><b><a href="#client">client:</a></b> a node in the Tor network,
      typically running on behalf of one user, that routes application
      connections over a series of <a href="#relay">relays</a>.</p>
      
      <a name="consensus"></a>
      <p><b><a href="#consensus">consensus:</a></b> a single document compiled
      and voted on by the <a href="#directory-authority">directory
      authorities</a> once per hour, ensuring that all
      <a href="#client">clients</a> have the same information about the
      <a href="#relay">relays</a> that make up the Tor network.</p>
      
      <a name="consensus-weight"></a>
      <p><b><a href="#consensus-weight">consensus weight:</a></b> a value
      assigned to a <a href="#relay">relay</a> that is based on bandwidth
      observed by the relay and bandwidth measured by the
      <a href="#directory-authority">directory authorities</a>, included in the
      hourly published <a href="#consensus">consensus</a>, and used by
      <a href="#client">clients</a> to select relays for their
      <a href="#circuit">circuits</a>.</p>
      
      <a name="directory-authority"></a>
      <p><b><a href="#directory-authority">directory authority:</a></b> a
      special-purpose <a href="#relay">relay</a> that maintains a list of
      currently-running relays and periodically publishes a
      <a href="#consensus">consensus</a> together with the other directory
      authorities.</p>
      
      <a name="directory-mirror"></a>
      <p><b><a href="#directory-mirror">directory mirror:</a></b> a
      <a href="#relay">relay</a> that provides a recent copy of directory
      information to clients, in order to reduce the load on
      <a href="#directory-authority">directory authorities</a>.</p>
      
      <a name="onion-service"></a>
      <p><b><a href="#onion-service">onion service:</a></b> a
      service (for example, a website or instant-messaging server) that is only
      accessible via the Tor network.</p>
      
      <a name="pluggable-transport"></a>
      <p><b><a href="#pluggable-transport">pluggable transport:</a></b> an
      alternative transport protocol provided by <a href="#bridge">bridges</a>
      and used by <a href="#client">clients</a> to circumvent transport-level
      blockings (for example, by ISPs or governments).</p>
      
      <a name="relay"></a>
      <p><b><a href="#relay">relay:</a></b> a publicly-listed node in the Tor
      network that forwards traffic on behalf of <a href="#client">clients</a>,
      and that registers itself with the
      <a href="#directory-authority">directory authorities</a>.</p>
      
      <a name="relay-flag"></a>
      <p><b><a href="#relay-flag">relay flag:</a></b> a special
      (dis-)qualification of <a href="#relay">relays</a> for circuit positions
      (for example, "Guard", "Exit", "BadExit"), circuit properties (for
      example, "Fast", "Stable"), or roles (for example, "Authority", "HSDir"),
      as assigned by the <a href="#directory-authority">directory
      authorities</a> and further defined in the
      <a href="https://gitweb.torproject.org/torspec.git/tree/dir-spec.txt">directory
      protocol specification</a>.</p>

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