Define software reliability and describe how practical measurements can be
made for the reliability of software systems.

Hi friend..

Software reliability is an important facet of software quality. It is defined as "the probability of failure-free operation of a computer program in a specified environment for a specified time".

one of reliability's distinguishing characteristics is that it is objective, measurable, and can be estimated, whereas much of software quality consists of subjective criteria.this distinction is especially important in the discipline of software quality assurance. These measured criteria are typically called software metrics.

common software metrics common software metrics include:
source lines of code cyclomatic complexity function point analysis bugs per line of code code coverage number of lines of customer requirements.

Number of classes and interfaces robert cecil martin’s software package metrics cohesion coupling limitations it is very difficult to satisfactorily define or measure "how much" software there is in a program, especially when making such a prediction prior to the detail design.

The practical utility of software metrics has thus been limited to narrow domains where the include:
schedule
size/complexity
cost quality
too much emphasis
on any one of these aspects of performance is likely to create an imbalance in the team’s motivations, leading to a dysfunctional project.

The balanced scorecard is a one tool for managing a suite of metrics that address multiple performance perspectives.

Thanks
deepasree