Recent Developments and Trends in CAPTCHA: A Review

The Completely Automated Public Turing test to Tell Computers and Humans Apart, or CAPTCHA, has changed significantly since it was first developed and is now a crucial line of defense against automated bots. This study examines the most recent developments in CAPTCHA design, their ability to fend off online attacks, and the difficulties associated with developing artificial intelligence (AI) methods. The paper examines the future direction of CAPTCHA technology and provides insights into new CAPTCHA types, their usability, and the best way to balance security and accessibility. The goal of recent advancements has been to create increasingly complex and intuitive CAPTCHA variants, such as behavior-based gamified audio-based and image-based systems. In an attempt to achieve a balance between security and accessibility, these developments address problems such as the computational overhead of difficult problems and usability for people with disabilities. However, because AI has made it possible for bots to circumvent conventional CAPTCHAs, it has also created new difficulties, particularly in domains like machine learning and adversarial networks. This article examines the most recent advancements in CAPTCHA technology and assesses how well they defend against contemporary threats. It also discusses recent research that aims to improve security and user experience. The purpose of this paper is to give a summary of the current state of advanced CAPTCHA and point out its flaws.