user3237: I know everyone will say that this is a stupid question, but I'm going to ask it anyway...
Is there a space between the move number and the move algebraic notation?
In other words, which of these is the correct notation? :
1.e4 e5 or 1. e4 e5 ?
26.Nxe4 or 26. Nxe4 ?
8...Bb4+ or 8... Bb4+ ?
I've seen both with and without the space. On Wikipedia there are spaces. But I checked in three of my books and there isn't any space in any of them.

user2800: As you already noted, both are used. Either style is acceptable, and engines, pgn viewers etc. will usually not have any problems with either of them. The most common is probably without the spaces though, especially with long series of moves it can be argued it improves the readability a bit by not having unnecessary extra spaces. In books the notation will probably always be without spaces if for no other reason than to conserve page space over the length of the book.

user933: From Portable Game Notation Specification and Implementation Guide:

7: Tokens
An integer token is a sequence of one or more decimal digit
  characters.  It is a special case of the more general "symbol" token
  class described below. Integer tokens are used to help represent move
  number indications (see below). An integer token is terminated just
  prior to the first non-symbol character following the integer digit
  sequence.
A period character (".") is a token by itself.  It is used for move
  number indications (see below).  It is self terminating.

and

8.2.2: Movetext move number indications
A move number indication is composed of one or more adjacent digits
  (an integer token) followed by zero or more periods.  The integer
  portion of the indication gives the move number of the immediately
  following white move (if present) and also the immediately following
  black move (if present)

So you see that, by spec, any spaces after move number doesn't matter at all.

3237: <p>I know everyone will say that this is a stupid question, but I'm going to ask it anyway...</p>

<p>Is there a space between the move number and the move algebraic notation?</p>

<p>In other words, which of these is the correct notation? :</p>

<p>1.e4 e5 or 1. e4 e5 ?</p>

<p>26.Nxe4 or 26. Nxe4 ?</p>

<p>8...Bb4+ or 8... Bb4+ ?</p>

<p>I've seen both with and without the space. On Wikipedia there are spaces. But I checked in three of my books and there isn't any space in any of them.</p>
 2800: <p>As you already noted, both are used. Either style is acceptable, and engines, pgn viewers etc. will usually not have any problems with either of them. The most common is probably without the spaces though, especially with long series of moves it can be argued it improves the readability a bit by not having unnecessary extra spaces. In books the notation will probably always be without spaces if for no other reason than to conserve page space over the length of the book.</p>
 933: <p>From <a href="http://www6.chessclub.com/help/PGN-spec" rel="noreferrer">Portable Game Notation Specification and Implementation Guide</a>:</p>

<blockquote>
  <h2>7: Tokens</h2>
  
  <p>An integer token is a sequence of one or more decimal digit
  characters.  It is a special case of the more general "symbol" token
  class described below. Integer tokens are used to help represent move
  number indications (see below). <strong>An integer token is terminated just
  prior to the first non-symbol character following the integer digit
  sequence.</strong></p>
  
  <p>A period character (".") is a token by itself.  It is used for move
  number indications (see below).  <strong>It is self terminating.</strong></p>
</blockquote>

<p>and</p>

<blockquote>
  <h2>8.2.2: Movetext move number indications</h2>
  
  <p>A move number indication is composed of one or more adjacent digits
  (<strong>an integer token</strong>) followed by zero or more <strong>periods</strong>.  The integer
  portion of the indication gives the move number of the immediately
  following white move (if present) and also the immediately following
  black move (if present)</p>
</blockquote>

<p>So you see that, by spec, any spaces after move number doesn't matter at all.</p>
