In software testing, a bug is an informal name for a defect, which means that software or an application is not working as per the requirement. A bug can also be referred to as an issue, error, fault, or failure. Bugs can occur due to various reasons such as wrong coding, missing coding, lack of communication, and logic errors. Common types of software bugs include functional bugs, logical bugs, workflow bugs, unit level bugs, system-level bugs, regression defects, and security vulnerabilities. Bug testing is an essential part of the software development process and helps to ensure that software is properly tested prior to launch. Identifying and resolving bugs during development is important to deliver a successful and user-friendly product.