GASP stands for: Growmap Anti Spambot Plugin
There was a plugin released for WordPress (G.A.S.P. Plugin) some time ago that did a great job at preventing WordPress comment spam by automated spambots. (The WordPress Shield Security plugin has integrated a much-improved version of this for comments protection).
GASP Protection on the login screen works in exactly the same manner.
Enabling this option will place a checkbox on the login screen:
How to enable this protection on your login form
To enable GASP protection on your login form, you'll need to select login form first, and then enable Bot Protection feature:
What does this feature protect me from?
If the server-side checks doesn't find this checkbox present, it'll reject the login process altogether.
Applications of this feature
There is no reason not to enable this feature. It has minimal impact on the logging-in user and is reliable in preventing automated login attempts to your site.
To learn more how to add GASP protection to the WordPress login screen, read our blog article here.