Application security is the general practice of adding features or functionality to software to prevent a range of different threats. These include denial of service attacks and other cyberattacks, and data breaches or data theft situations.
Techopedia explains Application Security
Different types of application security such as firewalls, antivirus programs, encryption programs and other devices can help to ensure that unauthorized access is prevented. Companies also can identify sensitive data assets and protect them through specific application security processes tied to these data sets.
Application security is one of several levels of security that companies use to protect systems. Others include operating system security, network security and end-point or mobile security.
All of these types of security are aimed at protecting clients and users of software from of hacking and malicious intent. In addition, application security is critical for mobile app stores, where hackers try to attach various kinds of malware to less vetted mobile apps.