diff --git a/static/style.css b/static/style.css
index e6c80dd..641e440 100644
--- a/static/style.css
+++ b/static/style.css
@@ -362,7 +362,7 @@ span.mono   { font-family: monospace; }
 span.light  { color: #CCC; }
 span.medium { color: #AAA; }
 
-span.source-confidence { font-weight: bold; }
+span.source-similarity { font-weight: bold; }
 span.source-suspect    { color: #900; }
 span.source-possible   { color: #990; }
 span.source-novio      { color: #090; }
diff --git a/templates/api.mako b/templates/api.mako
index befaf2f..226e6e0 100644
--- a/templates/api.mako
+++ b/templates/api.mako
@@ -116,7 +116,7 @@
                         <td>detail</td>
                         <td>boolean</td>
                         <td>No (default: <span class="code">false</span>)</td>
-                        <td>Whether to include the detailed HTML text comparison available in the regular interface. If not, only the confidence percentage is available.</td>
+                        <td>Whether to include the detailed HTML text comparison available in the regular interface. If not, only the similarity percentage is available.</td>
                     </tr>
                 </table>
                 <table class="parameters">
@@ -181,7 +181,7 @@
                         <td>noskip</td>
                         <td>boolean</td>
                         <td>No (default: <span class="code">false</span>)</td>
-                        <td>If a suspected source is found during a check to have a sufficiently high confidence value, the check will end prematurely, and other pending URLs will be skipped. Passing this option will prevent this behavior, resulting in complete (but more time-consuming) checks.</td>
+                        <td>If a suspected source is found during a check to have a sufficiently high similarity value, the check will end prematurely, and other pending URLs will be skipped. Passing this option will prevent this behavior, resulting in complete (but more time-consuming) checks.</td>
                     </tr>
                 </table>
                 <h2>Responses</h2>
@@ -213,13 +213,13 @@
     },
     "best": {
         "url":        <span class="resp-dtype">string</span> <span class="resp-desc">the URL of the best match found, or null if no matches were found</span>,
-        "confidence": <span class="resp-dtype">float</span> <span class="resp-desc">the confidence of a violation in the best match, or 0.0 if no matches were found</span>,
+        "confidence": <span class="resp-dtype">float</span> <span class="resp-desc">the similarity of a violation in the best match, or 0.0 if no matches were found</span>,
         "violation":  <span class="resp-dtype">string</span> <span class="resp-desc">one of "suspected", "possible", or "none"</span>
     },
     "sources": [
         {
             "url":        <span class="resp-dtype">string</span> <span class="resp-desc">the URL of the source</span>,
-            "confidence": <span class="resp-dtype">float</span> <span class="resp-desc">the confidence of a violation in the source</span>,
+            "confidence": <span class="resp-dtype">float</span> <span class="resp-desc">the similarity of the source to the page checked as a ratio between 0.0 and 1.0</span>,
             "violation":  <span class="resp-dtype">string</span> <span class="resp-desc">one of "suspected", "possible", or "none"</span>,
             "skipped":    <span class="resp-dtype">boolean</span> <span class="resp-desc">whether the source was skipped due to the check finishing early (see note about noskip above) or an exclusion</span>,
             "excluded":    <span class="resp-dtype">boolean</span> <span class="resp-desc">whether the source was skipped for being in the excluded URL list</span>
@@ -231,7 +231,7 @@
         "source":  <span class="resp-dtype">string</span> <span class="resp-desc">source text, with shared passages marked with HTML</span>
     }
 }</pre>
-                <p>In the case of <span class="code">action=search</span>, <span class="code">sources</span> will contain one entry for each source checked (or skipped if the check ends early), sorted in order of confidence, with skipped and excluded sources at the bottom.</p>
+                <p>In the case of <span class="code">action=search</span>, <span class="code">sources</span> will contain one entry for each source checked (or skipped if the check ends early), sorted by similarity, with skipped and excluded sources at the bottom.</p>
                 <p>In the case of <span class="code">action=compare</span>, <span class="code">best</span> will always contain information about the URL that was given, so <span class="code">response["best"]["url"]</span> will never be <span class="code">null</span>. Also, <span class="code">sources</span> will always contain one entry, with the same data as <span class="code">best</span>, since only one source is checked in comparison mode.</p>
                 <p>Valid responses for <span class="code">action=sites</span> are formatted like this:</p>
                 <pre>{
diff --git a/templates/index.mako b/templates/index.mako
index 1d4a1ac..fa5bc28 100644
--- a/templates/index.mako
+++ b/templates/index.mako
@@ -199,7 +199,7 @@
                         % endif
                     </div>
                     <div>${round(result.confidence * 100, 1)}%</div>
-                    <div>confidence</div>
+                    <div>similarity</div>
                 </td>
                 <td>
                     % if result.url:
@@ -252,7 +252,7 @@
                     </colgroup>
                     <tr>
                         <th>URL</th>
-                        <th>Confidence</th>
+                        <th>Similarity</th>
                         <th>Compare</th>
                     </tr>
                     % for i, source in enumerate(result.sources):
@@ -265,7 +265,7 @@
                                     <% skips = True %>
                                     <span class="source-skipped">Skipped</span>
                                 % else:
-                                    <span class="source-confidence ${"source-suspect" if source.confidence >= T_SUSPECT else "source-possible" if source.confidence >= T_POSSIBLE else "source-novio"}">${round(source.confidence * 100, 1)}%</span>
+                                    <span class="source-similarity ${"source-suspect" if source.confidence >= T_SUSPECT else "source-possible" if source.confidence >= T_POSSIBLE else "source-novio"}">${round(source.confidence * 100, 1)}%</span>
                                 % endif
                             </td>
                             <td>
@@ -281,12 +281,12 @@
             % endif
             % if len(result.sources) > 10:
                 <div id="cv-additional" class="cv-source-footer">
-                    ${len(result.sources) - 10} URL${"s" if len(result.sources) > 11 else ""} with lower confidence hidden. <a id="show-additional-sources" href="#">Show them.</a>
+                    ${len(result.sources) - 10} URL${"s" if len(result.sources) > 11 else ""} with lower similarity hidden. <a id="show-additional-sources" href="#">Show them.</a>
                 </div>
             % endif
             % if skips or result.possible_miss:
                 <div class="cv-source-footer">
-                    The search ended early because a match was found with high confidence. <a href="${request.url | httpsfix, h}&amp;noskip=1">Do a complete check.</a>
+                    The search ended early because a match was found with high similarity. <a href="${request.url | httpsfix, h}&amp;noskip=1">Do a complete check.</a>
                 </div>
             % endif
         </div>