ISO/IEC 25010

The quality model is the cornerstone of a product quality evaluation system. The quality model determines which quality characteristics will be taken into account when evaluating the properties of a software product.

The quality of a system is the degree to which the system satisfies the stated and implied needs of its various stakeholders, and thus provides value. Those stakeholders' needs (functionality, performance, security, maintainability, etc.) are precisely what is represented in the quality model, which categorizes the product quality into characteristics and sub-characteristics.

The product quality model defined in ISO/IEC 25010 comprises the nine quality characteristics shown in the following figure:

This characteristic represents the degree to which a product or system provides functions that meet stated and implied needs when used under specified conditions. This characteristic is composed of the following sub-characteristics:

• Functional completeness - Degree to which the set of functions covers all the specified tasks and intended users' objectives.
• Functional correctness - Degree to which a product or system provides accurate results when used by intended users.
• Functional appropriateness - Degree to which the functions facilitate the accomplishment of specified tasks and objectives.

This characteristic represents the degree to which a product performs its functions within specified time and throughput parameters and is efficient in the use of resources (such as CPU, memory, storage, network devices, energy, materials...) under specified conditions. This characteristic is composed of the following sub-characteristics:

• Time behaviour - Degree to which the response time and throughput rates of a product or system, when performing its functions, meet requirements.
• Resource utilization - Degree to which the amounts and types of resources used by a product or system, when performing its functions, meet requirements.
• Capacity - Degree to which the maximum limits of a product or system parameter meet requirements.

Degree to which a product, system or component can exchange information with other products, systems or components, and/or perform its required functions while sharing the same common environment and resources. This characteristic is composed of the following sub-characteristics:

• Co-existence - Degree to which a product can perform its required functions efficiently while sharing a common environment and resources with other products, without detrimental impact on any other product.
• Interoperability - Degree to which a system, product or component can exchange information with other products and mutually use the information that has been exchanged.

Degree to which a product or system can be interacted with by specified users to exchange information ia the user interfaceto complete specific tasks in a variety of contexts of use. This characteristic is composed of the following sub-characteristics:

• Appropriateness recognizability - Degree to which users can recognize whether a product or system is appropriate for their needs.
• Learnability - Degree to which the functions of a product or system can be learnt to be used by specified users within a specified amount of time.
• Operability - Degree to which a product or system has attributes that make it easy to operate and control.
• User error protection. Degree to which a system prevents users against operation errors.
• User engagement - Degree to which a user interface presents functions and information in an inviting and motivating manner encouraging continued interaction.
• Inclusivity - Degree to which a product or system can be used by people of various backgrounds (such as people of various ages, abilities, cultures, ethnicities, languages, genders, economic situations, etc.).
• User assistance - Degree to which a product can be used by people with the widest range of characteristics and capabilities to achieve specified goals in a specified context of use.
• Self-descriptiveness - Degree to wich a product presents appropriate information, where needed by the user, to make its capabilities and use immediately obvious to the user without excessive interactions with a product or other resources (such as user documentation, help desks or other users).