Service packs

A service pack comprises a collection of updates, fixes, or enhancements to a software program delivered in the form of a single installable package.

What does the SP1, SP2, SP3, SP4 and so on stand for?

In a normal software life cycle many service packs can be released to fix issues and develop new features based on the requirements. It includes enhancements and third-party integrations. Service packs are typically numbered to indicate the relevant version. SP2 (=Service Pack 2) is the second service pack for a software program. 

The list of service packs that have been shipped for Cloudera Data Services on premises 1.5.5 releases.