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Akismet is a good plugin to have enabled. It’s free for personal websites and is completely unobtrusive:

https://wordpress.org/plugins/akismet/

But think of your fight against spam as a ‘strategy’. No single plugin will do the job. You’ll probably need to deploy a combo of plugin(s), manual moderation etc. Spammers are always changing their tactics so your strategy will need to change from time to time also.