$().ready(function()
{
    $("#commentForm").validate(
    {
        rules:{
            name: { 
                required: true,
                minlength: 2
            },
            email: { 
                required: true, 
                email: true
            },
            content: { 
                required: true,
                minlength: 5
            },  
            captcha: { 
                required: true
            },  
        },
        messages: {
            captcha: { 
                required: "Please, enter captcha"
            },
            name: { 
                required: "Please, enter your name"
            },
            content: { 
                required: "Please, enter your comment"
            },   
            email: "Please, enter a valid email address"
        }
    });
});