Hi i am learning rails from the Odin project and i am creating a simple authentication without using devise . the course doesn’t really give enough info to help beginners finish that project

so, Here is the part that i don’t understand. the login method

class RegistrationController < ApplicationController
     def new
         @user.new
     end
      def create
         @user = User.new(registration_params)
        if @user.save
             login @user
             redirect_to root_path
        else
            render :new

class ApplicationController < ActionController::Base

    private
    
    def login(user)
        Current.user= user
        reset_session
        session[:user_id] = user.id
    end

i don’t understand what Current.user = user does

i can’t find anything for the “Current” object and is user a method in it?

the source code here seems hard for me to understand https://api.rubyonrails.org/classes/ActiveSupport/CurrentAttributes.html

thanks