To detect and classify bugs in an appropriate way, it is recommended to classify bugs based on a certain level. One can also take the assistance of defect tracking tools to make this entire process more convenient but to do that, you need to classify the issues based on some factors. 

A basic understanding of this categorization assists in handling the bugs more effectively. 

Why is defect classification significant?

Classification of bugs is worthy of attention as it enhances the quality of the program and the functioning of the applications. It helps in rationalizing and prioritizing the bugs that need to be fixed so the development process and testing efficiency can be increased.

The defects which can be detected based on its performance, usability, and security demonstrate the nature of those bugs.

Defects are mainly due to the logical errors in coding, which eventually attacks the security feature of the software, and as a result, it weakens the whole authorization access of the application and can allow access to sensitive information transmitted online. Usually, to rectify these all, defect tracking tools are used.

Not only this, but defects can also hamper the easy usage of the software by the customers and users, either because of a complex user interface, code, or intricate layout of application function. These defects disrupt for users to have a smooth run of the software. 

Furthermore, defects related to speed, and stability of a program can hamper the efficient performance of a software. These defects can also be caused by the slow processing time of a program as compared to the time required for it.

The main two parameters on which the bugs can be classified are known as Severity and Priority. How these two are different and who decides them is all discussed in detail below.

Defects Classified on Severity

The severity of a defect and bug can be analyzed by its technical impact on the functioning of the software. If a bug hampers the overall functioning of the program this shows its critical level of severity, which the testing team needs to track by using defect tracking tools. To measure the extent of the negative impact a bug can have on the quality of the software is indicated through this classification. Further, to elaborate this categorization the severity of bugs can be analyzed as per the following parameters:

  • Critical Severity is when the program cannot function at all. Either there is an error in the installation of the program or any specific feature has completely failed to function. For unknown reasons when the application crashes or is unusable then also the critical level of severity is considered.
  • Major Severity of defects is when there are multiple glitches on every step of the program, which can create difficulty in the functionality of that system. Any major feature when not meeting the requirements and performs differently is classified under major severity level.
  • Moderate Severity is when the impact of the error on the functionality of a program can be overseen and it is not affecting the software on an extreme level.
  • Trivial Severity defects don’t need an immediate fix, because they neither limit the functionality of the program nor impacts its productivity.

Defects Classified on Priority/Urgency

The urgent and immediate rectification of some bugs in which the defect tracking tools look into it based on priority. In Software testing, prioritizing the detection of bugs is one of the key roles of a Product Manager as he manages the overall product. Therefore an understanding of bugs that can have more impact on the business and need instant identification can be done by prioritizing it. When there are a large number of defects then the testing team needs to manage the hierarchy of detection and fixing of bugs based on urgency and priority. 

  • Urgent
  • Medium Priority
  • Minor-Priority
  • Low-Priority


Classification of defects is important to be documented and understood by the testers as it can help in immediate detecting and fixing of the bugs throughout the development process of programs. All stakeholders involved in business have their subjective definition for these defects of severity and priority. The above classification will act as guidance for both the testers and management teams to select the right level of severity and priority of the defects. Allocating the correct severity level of defects by the tester is further going to help in selecting the priority level of that bug. These two terms should never be mixed or used interchangeably.

Also Read: 8 Must-Have Tools for Software Development Teams