The security of the application means many different things to many different people. In the IEEE Security & Privacy magazine, it has come to mean the protection of the software once it is already built. Although the notion of protecting software is important, it is much easier to protect something that is free of defects than something riddled with vulnerabilities.
Application security is naturally based on a network-centric security approach, adopting standard approaches such as penetrating and applying patches  and inbound filtering (trying to block malicious entries) and providing value in a reactive way . In short, application security is mainly based on finding and solving known security problems after they have been exploited in systems in the field. Software security, the process of designing, creating and testing software for security, identifies and eliminates problems in the software itself. In this way, software security professionals try to create software that can resist the attack proactively. Let me give you a specific example: although there is a real value in stopping buffer overflow attacks by observing HTTP traffic as it arrives on port 80, a superior approach is to fix the broken code and avoid the buffer overflow completely.
Software security is the idea of engineering software so that it continues to function properly under malicious attack. Most technologists recognize the importance of this company, but they need help to understand how to approach it. This new department aims to provide that help by exploring the best software security practices.
The security field of the software is relatively new. The first books and academic classes on the subject appeared in 2001, demonstrating how recently developers, architects and computer scientists have begun to systematically study how to build secure software. The recent appearance of the field is one of the reasons why best practices are not widely adopted or obvious.