• Priyanka Thakur
• Rahul Chawda

Applications are with the end goal that they are powerful against information of all structures be it client, database or some other outer element. CAPTCHA represent Completely Automated Public Turning Test to Tell Computers and Humans. It is a test that validated clients need to breeze through the test to access their particular mail accounts. It is significant for a CAPTCHA to be both clear for people and solid against pernicious PC programs. As of late, PC vision and example acknowledgment calculations have broken some outstanding CAPTCHAs. In this paper, we present current CAPTCHAs and assaults against them; we research the strength and ease of use of ebb and flow CAPTCHAs and talk about plans to grow progressively powerful and usable CAPTCHAs

CAPTCHA, Text Based CAPTCHA, Image Based CAPTCHA, Audio/Video Based CAPTCHA

"A Survey about CAPTCHA Based Security Techniques", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.6, Issue 5, page no.372-375, May-2019, Available :http://www.jetir.org/papers/JETIR1905155.pdf

"A Survey about CAPTCHA Based Security Techniques", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.6, Issue 5, page no. pp372-375, May-2019, Available at : http://www.jetir.org/papers/JETIR1905155.pdf