SharePoint 2010 : Naming conventions for files,folders and sites

Sharing some basic information that may take a while to find on the web-

SharePoint 2010 guidelines for Site names, subsite names, or site group names

•You cannot use the following characters anywhere in a site name, in a subsite name, or in a site or Active Directory group name:

• tilde (~)
• number sign (#)
• percent (%)
• ampersand (&)
• asterisk (*)
• braces ({ })
• backslash (\)
• colon (:)
• angle brackets (<,>)
• question mark (?)
• slash (/)
• plus sign (+)
• pipe (||)
• quotation mark (")

•You cannot start a site name, subsite name, or a site group name with an underscore (_) character or with the period character.

•You cannot use the period character consecutively in the middle of a site name, a subsite name, or a site group name.

•You cannot use the period character at the end of a site name, a subsite name, or a site group name.

Folder names

•You cannot use the following characters anywhere in a folder name or a server name:

• tilde (~)
• number sign (#)
• percent (%)
• ampersand ("&")
• asterisk (*) 
• braces ({ })
• backslash (\)
• colon (:)
• angle brackets "<",">")
• question mark (?)
• slash (/)
• plus sign (+)
• pipe ("||") 
• quotation mark (")

 
 

•You cannot use the period character consecutively in the middle of a folder name.

•You cannot use the period character at the end of a folder name.

•You cannot start a folder name with the period character.

File names

•You cannot use the following characters anywhere in a file name:

• tilde (~)
• number sign (#)
• percent (%)
• ampersand ("&")
• asterisk (*)
• braces ({ })
• backslash (\)
• colon (:)
• angle brackets "<",">")
• question mark (?)
• slash (/)
• plus sign (+)
• pipe ("||")
• quotation mark (")

•You cannot use the period character consecutively in the middle of a file name.

•You cannot use the period character at the end of a file name.

•You cannot start a file name with the period character.

•In addition, file names and folder names may not end with:

• .files
• _files
• -Dateien
• _fichiers
• _bestanden
• _file
• _archivos
• -filer
• _tiedostot
• _pliki
• _soubory
• _elemei
• _ficheiros
• _arquivos
• _dosyalar
• _datoteke
• _fitxers
• _failid
• _fails
• _bylos
• _fajlovi
• _fitxategiak

Courtesy :
http://support.microsoft.com/kb/905231