SAP S/4 HANA – SAP’S next generation business suite.
In Feb 2015, SAP introduced S/4 HANA. SAP S/4 HANA is short for SAP Business Suite 4 SAP HANA.
SAP marketing it as their biggest innovation since R/3.
At its launch event in New York, SAP executive CEO Bill McDermott referred S/4 HANA as Simple fourth generation HANA.

SAP Major Product release time line:
SAP Major product release
Core principals
SAP S/4HANA delivers massive simplifications in all aspect of application - customer adoption, data model, user experience, business processes. It’s SAP response to new generation innovations (Internet of Things, Big Data and mobile).

S/4 HANA is based on following principals:

Simplified Data models
Completely Fiori
Guided configuration.

Simple data models: Since S/4 HANA is based on HANA, With HANA SAP got luxury to redesign the core process flow eliminating aggregates, indices and redundant tables. They drastically reduced the number of tables required for all major transaction processing.
For example a finance application which was running with more than 20 tables, can now be supported with 4 tables. SAP introduced Simple finance powered by SAP HANA and it lies at the core of S/4 HANA.
  
Completely Fiori: Thanks to Fiori, SAP finally updated their User interface and it’s a major welcoming change. It’s a HTML5/UI5 based user interface supported on all kind of devices. It will run smoothly on tablets, mobile and even on smart watches.
  
Guided Configuration: S/4 HANA is a role based application and it uses step by step guided process flow to walk you through the tasks. This will reduce the learning curve for end users. Developers can customize/configure this guided process flow.

Deployment Options
Since S/4 HANA is fueled by HANA it gives all the installation options provide by HANA - On-premise, Cloud (managed and public) and Hybrid. Currently SAP opened up with on-premise installation only and later this year they will open the other two options too.

 Where S/4 HANA fits in HANA bandwagon?
HANA product release time line

It all started in 2011 with launch of HANA as a DB and Application platform. It was first Row + Column based database which resides completely in memory. Being a columnar database it has various advantages like huge compression ratio and faster read operations. This was a perfect product to run OLAP application and hence SAP launched Business Warehouse (BW) on HANA in 2012.

Till then, only OLAP applications were supported by HANA and in 2013, SAP changed the game by running OLTP and OLAP combined in HANA .They introduced Business suite running on HANA as primary database. SAP optimized the core of its Business suite application to take advantage of HANA.

Since they have established the concept that an OLTP system can run on an in-memory columnar database, they started working on a complete simplified redesign of their Business Suit. They slimmed down the data models and that gave another boost to performance. 

In 2014 they introduced SAP Simple Finance - a new advanced version of ERP finance running with simplified redundancy free data models promoting single point of truth.

At the top of the chain, in 2015 SAP introduced S/4 HANA based on concept of simplified, real time data models supported by SAP HANA, SAP FIORI.

 Advantages of S/4 HANA
Multi tenancy: S/4 HANA takes advantages of HANA's multi tenancy feature , with this option we can run ECC and CRM or any other satellite system on one box. A typical ECC - CRM data transfer accounts for 60% of overall system load, with this multi tenancy option this data transfer load will go away.
Simplified Data models: SAP removed the redundant tables required for aggregates and indices. This leads us to fewer table to work upon, that means less table locks, less data to manipulate and better performance.
Guided procedures results in faster rollout and reduced learning curve for end users.
Agile implementation:  With S/4 HANA SAP gave us the option to easily integrate with cloud applications like Ariba , SuccessFactor , Big Data and even IoT(internet of things). This leads us to faster and simplified integration.
Real time insight: With S/4 HANA we got access to real time data insights which helps us in decision making, less efforts in planning, simulation, execution and prediction.
Less time to market: New customers can take advantage of prebuilt functionality and with minimal customization a new product or a business line can be plugged into the system.
Reduced TCO because of smaller IT landscape footprint, Simplified data models, faster rollouts, reduced learning curve and more productivity because of faster systems and guided procedures.