Want to know your SharePoint version?

There are several ways to get your SharePoint version. Here are some:

1. You can get the SharePoint version in central administration. Go to CA > Operations >  Servers in Farm (under Topology and Services)

2. You can identify the SharePoint version from Installed Programs. Go to Control Panel > Add and Remove Programs. Select SharePoint server and then click: Click here for support. Now a window will pop up that displays your current SharePoint version.

3. Open your SharePoint site in SharePoint Designer (can be the main site or any sub-site), click Site Settings under the Site menu on the top toolbar. You’ll find the version of SharePoint running the site on the general tab under SharePoint version

4. Open any of your SharePoint site, go to Site Actions >Site Settings. The version is just below Site Information.

You can use the below code, If you wan to get the version programmatically:

using (SPSite startSite = new SPSite("<Central Admin url>"))
{
 SPFarm farm = startSite.WebApplication.Farm;
 SPWebService service = farm.Services.GetValue<SPWebService>("");

     foreach (SPWebApplication webApplication in service.WebApplications)
       {
       foreach (SPSite site in webApplication.Sites)
          {
             Console.WriteLine(string.Format("{0} - {1}", site.Url, site.ContentDatabase.Name));
          }
       }
 }

PowerShell Way to get SharePoint Installed Version:

$farm = [Microsoft.SharePoint.Administration.SPFarm]::Local
$farm.BuildVersion.ToString()

If you want to know What version of MOSS is installed (Standard or Enterprise), you can look in Central Administration > Operations > Convert License Type 

Here is the link to determine the service packs/updates based on version number: https://buildnumbers.wordpress.com/sharepoint/