4.22.3 ‘Attempt authentication using Pageant’

If this option is enabled, then PuTTY will look for Pageant (the SSH private-key storage agent) and attempt to authenticate with any suitable public keys Pageant currently holds.

This behaviour is almost always desirable, and is therefore enabled by default. In rare cases you might need to turn it off in order to force authentication by some non-public-key method such as passwords.

This option can also be controlled using the -noagent command-line option. See section 3.8.3.9.

See chapter 9 for more information about Pageant in general.