What is Defect severity?

Severity of bug is an extreme level of damage like financial loss, company’s reputation and loss of life, due to presence of the bug. Example such as if point of sales machine does not function as expected, and does not dispense bill, thereby customer may not pay the amount for the purchases, in such situation, the defect due to which bills are not displaying amount of purchase, is termed as severe test case, as due to such defect, there will be huge financial loss. Further say, infrared machine that used for removing decay in the teeth malfunction and damages the jaw of patient, it may result into loss of life.
Defect severity are categorized into following levels
Blocker – Due to this defect type, it becomes impossible to further run the application, there for the name – Blocker
Critical – There are some workarounds to accomplish the task, e.g. pdf format of file type is not downloaded, whereas word type is possible.
Major – some error may lead to understanding the title or content by end user, e.g. software display s title and content in English, but does not display some of the title in Arabic language, but display it in English only.
Minor – there are some defects which has very minor impact on functionality of application, e.g. missing space between words, commas are missed in sentences.
Low –These defects does not impact at all, however if fixed it will be aesthetically pleasing, eg. Size of button, form border go out of screen and need to scroll in order to view the content.