whats does if(variable ) means in c language? : I m currently preparing for gate , I have come across a question

    #include<stdio.h>
    main()
    {
    static int var=6;
    printf("%d\t",var--);
    if(var)
    main();
    }

output is 6 5 4 3 2 1

i wanna know why it terminated after 1??

