WINRM is introduced in Windows Server 2003 R2. It is very similar to SysInternals “psexec“ tool. The new version WINRM is 2. WINRM is working on http. That is working with PowerShell. We can run windows command (netstat, ipconfig & etc) in a remote system through Invoke-command.  WINRM 1 worked on port 80, but WINRM version 2 works on port 5985. Normal PowerShell cmdlet is using RPC connection, but WINRM is working on hyper text transfer Protocol. By default 5 users & 5 connections for each user can be created, which means 25 total connections, but you can change that configuration. Also WINRM works on cmd prompt & it is not PowerShell dependent but it is working along with PowerShell. WINRM (Windows Remote Management) is a remote management like RDP, LDAP.

WinRM (Windows Remote Management) Troubleshooting
http://blogs.technet.com/b/jonjor/archive/2009/01/09/winrm-windows-remote-management-troubleshooting.aspx

Administrator's Guide to Powershell Remoting
http://powershell.com/cs/media/p/7257.aspx  

Enable and configure Windows PowerShell Remoting using Group Policy
http://blog.powershell.no/2010/03/04/enable-and-configure-windows-powershell-remoting-using-group-policy/  

Configuring WSMAN Limits
http://blogs.msdn.com/b/powershell/archive/2010/05/03/configuring-wsman-limits.aspx 

About Windows Remote Management
http://msdn.microsoft.com/en-us/library/aa384291(v=vs.85).aspx 

What's New in WinRM 2.0
http://msdn.microsoft.com/en-us/library/ee309369(v=vs.85).aspx 

Installation and Configuration for Windows Remote Management
http://msdn.microsoft.com/en-us/library/aa384372(v=vs.85).aspx 

Windows Remote Management Architecture
http://msdn.microsoft.com/en-us/library/aa384464(v=vs.85).aspx 

WS-Management Protocol
http://msdn.microsoft.com/en-us/library/aa384470(v=vs.85).aspx 

Scripting in Windows Remote Management
http://msdn.microsoft.com/en-us/library/aa384438(v=vs.85).aspx 

Authentication for Remote Connections
http://msdn.microsoft.com/en-us/library/aa384295(v=vs.85).aspx 

Proxy Servers and WinRM
http://msdn.microsoft.com/en-us/library/ee309366(v=vs.85).aspx 

Windows Remote Management and WMI
http://msdn.microsoft.com/en-us/library/aa384463(v=vs.85).aspx 

DMTF Profile Discovery Through Association Traversal
http://msdn.microsoft.com/en-us/library/ee309363(v=vs.85).aspx 

Infrastructure for Managing Hosted Services
http://msdn.microsoft.com/en-us/library/ee309370(v=vs.85).aspx 

IIS Host Plug-in Configuration
http://msdn.microsoft.com/en-us/library/ee309364(v=vs.85).aspx 

WinRM Service Plug-in Configuration
http://msdn.microsoft.com/en-us/library/ee309372(v=vs.85).aspx 

Remote Shell Infrastructure Improvements
http://msdn.microsoft.com/en-us/library/ee309368(v=vs.85).aspx 

Multi-Hop Support in WinRM
http://msdn.microsoft.com/en-us/library/ee309365(v=vs.85).aspx 

Quota Management for Remote Shells

http://msdn.microsoft.com/en-us/library/ee309367(v=vs.85).aspx

PowerShell Remoting Protocol Documentation Available
http://blogs.msdn.com/b/powershell/archive/2009/06/23/powershell-remoting-protocol-documentation-available.aspx