How to change to registeration captcha

When I register at the Elgg commnity forum, I noticed that I had to click on all these different images instead of typing in the captcha letters.


My question is, how do I add those pictures/security features to my site? Is that a plugin?



Beginning Developers

Beginning Developers

This space is for newcomers, who wish to build a new plugin or to customize an existing one to their liking