Stack Overflow does not use Captcha for verification anymore, how can they defend against bots?
14865
How often do CAPTCHAs appear?
118043
How to prevent robots from automatically filling up a form?
98119
Add optional box for spam flags letting you say why you think it's spam
95312
Does Stack Exchange prevent cheating with "fake" accounts?
158403
How to avoid getting spam through a website?
25280
Two factor authentication for Stack Exchange
66454
Why doesn't the Stack Overflow team fix the Firesheep style cookie theft?
156823
What can be done about the massive Close Votes queue on Stack Overflow?
105481
Preventing Brute Force Logins on Websites
41394
Logins can be added/removed without reauthenticating, allowing temporary XSS to be escalated to permanent account hijacking
151912
Raise an automatic flag for spammers
1941
How can I encourage Stack Overflow to rein in the 'subjective' vigilantes?
59556
Can Stack Overflow change the password criteria?
146331
Robots denied by domain is still listed in search results
29037
Remove XSS attacks while still allowing html?
97906
What can we do to prevent people from posting their coding questions on Meta?
151059
How to investigate Stack Overflow account hacking that resulted in answering some question inappropriately?