This Article contains a list of SharePoint 2013 version numbers and related updates.
Service packs include all previous updates and therefore if a service pack is listed below you do not need to download and Install previous CUHotfixesUpdates.
Please Note: As a result of the new packaging, it is no longer necessary to install the SharePoint Foundation cumulative update and then install the SharePoint Server cumulative update.
Some updates will require to run the SharePoint 2013 Products and Configuration Wizard (Navigate to Start – Microsoft SharePoint 2013 Products – SharePoint 2013 Products and Configuration Wizard)
April 2013 update
|SharePoint Foundation 2013
||SharePoint Server 2013
March 2013 update
More information available here for SharePoint FoundationServerproject 2013: http://technet.microsoft.com/en-US/sharepoint/jj891062
Office Web Application 2013 http://blogs.technet.com/b/office_sustained_engineering/
If the upgrade process fails run psconfig.exe -cmd upgrade -inplace b2b , if you recieve a update not applied error even if the update has been applied run psconfig.exe-cmd installcheck -noinstallcheck
To check the upgrade status you can run stsadm.exe -o localupgradestatus to kick of the process.