Explain the following software quality attributes: Performance, Scalability, Modifiability, Security, Availability, and Useability

Performance: This refers to the efficiency of a software application. It measures how well the software responds to user commands, how fast it processes data, and how little resources (like memory or CPU time) it uses in the process. High performance software is quick, efficient, and does not waste system resources.

Scalability: This is the ability of a software system to handle increased workloads. A scalable system is one that can handle an increase in users, data volume, or transactions without suffering a loss in performance. Scalability can be achieved through efficient use of resources, good design, and the ability to distribute workloads across multiple servers or systems.

Modifiability: This refers to how easily a software system can be changed to add new features, modify existing ones, or fix bugs. Modifiability is important because it allows a software system to adapt to changing user needs or business requirements. It is often achieved through good design practices, such as modular design and the use of design patterns.

Security: This is the ability of a software system to resist unauthorized access or attacks. A secure system is one that protects user data, prevents unauthorized access, and can recover quickly from attacks. Security is often achieved through the use of encryption, secure coding practices, and regular security audits.

Availability: This is the ability of a software system to be operational and accessible when needed. High availability systems are designed to be operational 24/7, and often have redundancy built in to handle system failures. Availability is often measured as a percentage, with 99.999% (or "five nines") availability being a common goal.

Usability: This refers to how easy a software system is to use. A usable system is one that is intuitive, easy to learn, and efficient to use. Usability is often achieved through good user interface design, user testing, and the use of user-centered design principles.