Attributes which all softwares should have

The important attributes are paraphrased below:
1. Reliability: Software Reliability is the probability of failure-free software operation for a specified period of time in a specified environment. Software Reliability is also an important factor affecting system reliability. It differs from hardware reliability in that it reflects the design perfection, rather than manufacturing perfection. The high complexity of software is the major contributing factor of Software Reliability problems. Software reliability is a key part in software quality. The study of software reliability can be categorized into three parts: modeling, measurement and improvement.

Software Reliability is an important to attribute of software quality, together with functionality, usability, performance, serviceability, capability, maintainability, and documentation

2. Dependability: Dependability is obviously a desirable system attribute. Even if a system is designed to be “dependable,” it is likely that it will need maintenance at some point in its life. Generally, if a system is designed poorly, maintenance cannot improve its poor performance. Maintenance can simply restore or prolong a previous state of operation. Of course, a poorly designed system could be retrofitted during a maintenance procedure, but retrofitting goes further than maintenance.

3. Correctness: The system should be producing the correct result. A program is functionally correct if it behaves according to the specification of the functions it should provide. The definition of the correctness assumes that a specification of the system is available. Correctness is a mathematical property that establishes the equivalence between the software and its specifications.

4. Portability: Portability is one of the key concepts of high-level programming. Portability is the software code base feature to be able to reuse the existing code instead of creating new code when moving software from an environment to another. The prerequirement for portability is the generalized abstraction between the application logic and system interfaces. When one is targeting several platforms with the same application, portability is the key issue for development cost reduction.
The action of moving software from a platform to another is called porting.

5. Modularity: Modular programming is subdividing your program into separate subprograms such as functions and subroutines. Subprograms make your actual program shorter, hence easier to read and understand. Modular programming can be used to break up a large program into manageable units, or to create code that can be easily re-used.  A modular program consists of a main module and one or more auxiliary modules.  Each module originates from a separate source code file.