Cloud is used in now a days.Before that what technology is used?
Before there was cloud computing, there was service oriented architecture (SOA). While cloud encompasses implementation and application delivery options, SOA is concerned with the foundation underneath that makes it all possible.
The bottom line is without SOA, it's very difficult to get to cloud. An elevator-pitch definition of service oriented architecture would be: Loosely-coupled services with well-defined interfaces that provide business functionality and can be shared or reused across and beyond the enterprise. These services can be discovered through a registry/repository or other directory, and can be assembled and dis-assembled to meet current business process demands.