The “Recaptcha for Login and Registration” extension is a plugin that allows users to add a captcha on their login and registration pages. The main purpose of this plugin is to allow users to securely authorize their subscribers or customers to create an account on their websites. I'm confident this will go a long way in preventing spammers from creating accounts on remote users' WordPress sites. Currently available in English, the code is ready to be translated.
A captcha is a program designed to distinguish human input from machine input. Spam often uses programming languages to crawl websites. Spammers use code to submit information without being physically present at a computer. This may result in receiving a lot of unsolicited emails or having users who are not real "customers". In some extreme cases, spammers find a way to hack your site when it is unprotected.
No, Google Recaptcha is not the only option. There are many types of captcha, such as math problems, WordPress problems. In my opinion, Google Recaptcha is the most popular.
Google Recaptcha v3 is the latest version. One of its particularities is that it does not necessarily appear to all users. Unlike version 2, where all users had to check the box before accessing the site, V3 will only pop up the box if the system suspects the presence of spam.