You can also identify service pack, international client pack, and hotfix numbers from the forth element of the version number, as described below.
Primary and Secondary Version Number
As Microsoft develops a software product new functions or features are added, major new features may be indicated with a new primary version number, minor functions or features will increment the secondary version number. For example: I am currently running Internet Explorer version 5.50.4807.2300. The primary and secondary version is 5.50. The build number is 4807 and 2300 identifies service pack 2 and hotfix 300.Build Number
Higher version and build numbers are always later and will not be overwritten with earlier version and build numbers during a Service Pack installation or upgrade. Service Pack
The leftmost digit, .x000, is the service pack release number (for example, 2.00.1239.2000 denotes Service Pack 2). By default service pack 2 will contain all of service pack 1. Microsoft documents all components of each service pack on their website " class="external">http://support.microsoft.com
International Client Packs
The ICP version number is represented by the second digit, which can range from 4 to 9 (.0400, .0500, .0600, .0700, .0800, .0900). Microsoft supports the following languages with International Client Packs: Arabic, Chinese (Simplified), Chinese (Traditional), Czech, Danish, Dutch, English, Finnish, French, German, Greek, Hebrew, Hungarian, Italian, Japanese, Korean, Norwegian, Polish, Portuguese (Brazilian), Portuguese, Russian, Spanish, Swedish, and Turkish.