Answers.Body: <p>I dont think that the OP mis-spelt. S/he really meant penned in and not pinned in.</p>
  
  <p>Penned in is a phrase meaning to be confined in an enclosure. From the MacMillan dictionary online.</p>
  
  <ol>
  <li><p>same as pen<br>
  We penned the sheep in for the night.</p></li>
  <li><p>to make it impossible for someone to get out of a place<br>
  A van was parked behind me, penning me in.</p></li>
  <li><p>to make someone feel that they cannot escape from a situation.</p></li>
  </ol>
  
  <p>The application in chess would be to situations where a Bishops mobility is blocked by other pieces, usually pawns, as in the post by @Glorfindel</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-09-11T07:55:16.933Z
Answers.Text: If you look at the revision history, you will see the OP spelt it *"pinned in"*.
Answers.UserDisplayName: Dag Oskar Madsen
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Answers.CreationDate: 2017-09-10T22:23:26.490Z
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Answers.LastEditDate: 2017-09-11T07:53:08.993Z
Answers.UserDisplayName: Philip Roe
Answers.Body: <p>I believe Brian Towers and user58697 are correct, and the author wrote/meant <em>pen</em> instead of <em>pin</em>. The <a href="https://www.merriam-webster.com/dictionary/pen" rel="noreferrer">dictionary</a> tells it's a small enclosure for animals, or an abbreviation for <a href="https://www.merriam-webster.com/dictionary/penitentiary" rel="noreferrer">penitentiary</a>, which seems more appropriate. Still, it's the first time I encounter this word in a chess setting, so it's not common and the confusion is understandable. </p>
  
  <hr>
  
  <p>While @Bad_Bishop provides the general (and, AFAIK, only common) use of the term <em>pin</em> in chess, I believe the author of your quote meant something along the lines of</p>
  
  <blockquote>
    <p>Bishops are worth more than knights except when they are blocked by their own pawns.</p>
  </blockquote>
  
  <p>(which matches your thoughts on the subject). Ironically, those bishops are often called <a href="https://en.wikipedia.org/wiki/Glossary_of_chess#Bad_bishop" rel="noreferrer">bad bishops</a>, like the white one in the diagram below:</p>
  
  <pre><code>[FEN "8/5pp1/3bp2p/1p1p4/1P1P4/2B1P2P/5PP1/8 w - - 0 1"]
  </code></pre>
  
  <p>One could argue that all pieces (including rooks and queens) have the same value when pinned (as in the common use of the word), but this is not entirely true; a pinned piece still prevents the opposing king from moving to certain fields, and a pinned bishop covers more squares than a pinned knight.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-09-10T19:33:20.887Z
Answers.Text: That's kind of what I thought it mean. A bishop has control over more squares when they are not blocked so it makes logical sense. Thanks for the analysis.
Answers.UserDisplayName: Marco V
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Answers.CreationDate: 2017-09-10T19:11:36.783Z
Answers.LastActivityDate: 2017-09-11T07:24:57.423Z
Answers.LastEditDate: 2017-09-11T07:24:57.423Z
Answers.UserDisplayName: Glorfindel
Body: <blockquote>
    <p>Bishops are worth more than knights except when they are penned in.</p>
  </blockquote>
  
  <p>What is meant by penned in? Does that mean that they are blocked by other pieces?</p>
  
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2017-09-11T04:58:36.300Z
Comments.Text: `pen` is an enclosure for livestock, so yes being `penned` means to be contained in a restricted area.
Comments.UserDisplayName: user58697
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2017-09-13T17:06:50.787Z
Comments.Text: Well I actually found the term here: 
  
  http://www.chessmaniac.com/64-chess-principles/
  
  Rule number 58.
Comments.UserDisplayName: Marco V
Tags: <terminology><bishops>
Title: What does "penned in" mean in Chess?
ThreadText: # What does "penned in" mean in Chess?
  
  (Asked by: username_0 on 2017-09-10)
  
  > Bishops are worth more than knights except when they are penned in.
  
  What is meant by penned in? Does that mean that they are blocked by other pieces?
  
  **Tags:** terminology, bishops
  
  > **Comments:**
  > **username_1**: `pen` is an enclosure for livestock, so yes being `penned` means to be contained in a restricted area.  
  > **username_0**: Well I actually found the term here:   http://www.chessmaniac.com/64-chess-principles/  Rule number 58.  
  
  ---
  
  ## 2 answers
  
  ### Answer by username_4 on 2017-09-10. Score: 14 | Accepted answer
  
  I believe Brian Towers and username_1 are correct, and the author wrote/meant *pen* instead of *pin*. The [dictionary](https://www.merriam-webster.com/dictionary/pen) tells it's a small enclosure for animals, or an abbreviation for [penitentiary](https://www.merriam-webster.com/dictionary/penitentiary), which seems more appropriate. Still, it's the first time I encounter this word in a chess setting, so it's not common and the confusion is understandable.
  
  ---
  
  While @Bad\_Bishop provides the general (and, AFAIK, only common) use of the term *pin* in chess, I believe the author of your quote meant something along the lines of
  
  > Bishops are worth more than knights except when they are blocked by their own pawns.
  
  (which matches your thoughts on the subject). Ironically, those bishops are often called [bad bishops](https://en.wikipedia.org/wiki/Glossary_of_chess#Bad_bishop), like the white one in the diagram below:
  
  ```
  [FEN "8/5pp1/3bp2p/1p1p4/1P1P4/2B1P2P/5PP1/8 w - - 0 1"]
  
  ```
  
  One could argue that all pieces (including rooks and queens) have the same value when pinned (as in the common use of the word), but this is not entirely true; a pinned piece still prevents the opposing king from moving to certain fields, and a pinned bishop covers more squares than a pinned knight.
  
  > **Comments:**
  > **username_0**: That's kind of what I thought it mean. A bishop has control over more squares when they are not blocked so it makes logical sense. Thanks for the analysis.  
  
  ---
  
  ### Answer by username_2 on 2017-09-10. Score: 5
  
  I dont think that the OP mis-spelt. S/he really meant penned in and not pinned in.
  
  Penned in is a phrase meaning to be confined in an enclosure. From the MacMillan dictionary online.
  
  1. same as pen  
     We penned the sheep in for the night.
  2. to make it impossible for someone to get out of a place  
     A van was parked behind me, penning me in.
  3. to make someone feel that they cannot escape from a situation.
  
  The application in chess would be to situations where a Bishops mobility is blocked by other pieces, usually pawns, as in the post by @username_4
  
  > **Comments:**
  > **username_3**: If you look at the revision history, you will see the OP spelt it *"pinned in"*.  
  
  ---
  
  