Bootstrap with jQuery Validation Plugin

For full compatibility with Bootstrap 3 I added support for input-group, radio and checkbox, that was missing in the other solutions.

Update 10/20/2017: Inspected suggestions of the other answers and added additional support for special markup of radio-inline, better error placement for a group of radios or checkboxes and added support for a custom .novalidation class to prevent validation of controls. Hope this helps and thanks for the suggestions.

After including the validation plugin add the following call:

$.validator.setDefaults({
    errorElement: "span",
    errorClass: "help-block",
    highlight: function (element, errorClass, validClass) {
        // Only validation controls
        if (!$(element).hasClass('novalidation')) {
            $(element).closest('.form-group').removeClass('has-success').addClass('has-error');
        }
    },
    unhighlight: function (element, errorClass, validClass) {
        // Only validation controls
        if (!$(element).hasClass('novalidation')) {
            $(element).closest('.form-group').removeClass('has-error').addClass('has-success');
        }
    },
    errorPlacement: function (error, element) {
        if (element.parent('.input-group').length) {
            error.insertAfter(element.parent());
        }
        else if (element.prop('type') === 'radio' && element.parent('.radio-inline').length) {
            error.insertAfter(element.parent().parent());
        }
        else if (element.prop('type') === 'checkbox' || element.prop('type') === 'radio') {
            error.appendTo(element.parent().parent());
        }
        else {
            error.insertAfter(element);
        }
    }
});

This works for all Bootstrap 3 form classes. If you use a horizontal form you have to use the following markup. This ensures that the help-block text respects the validation states ("has-error", ...) of the form-group.

<div class="form-group">
    <div class="col-lg-12">
        <div class="checkbox">
            <label id="LabelConfirm" for="CheckBoxConfirm">
                <input type="checkbox" name="CheckBoxConfirm" id="CheckBoxConfirm" required="required" />
                I have read all the information 
            </label>
        </div>
    </div>
</div>

for total compatibility with twitter bootstrap 3, I need to override some plugins methods:

// override jquery validate plugin defaults
$.validator.setDefaults({
    highlight: function(element) {
        $(element).closest('.form-group').addClass('has-error');
    },
    unhighlight: function(element) {
        $(element).closest('.form-group').removeClass('has-error');
    },
    errorElement: 'span',
    errorClass: 'help-block',
    errorPlacement: function(error, element) {
        if(element.parent('.input-group').length) {
            error.insertAfter(element.parent());
        } else {
            error.insertAfter(element);
        }
    }
});

See Example: http://jsfiddle.net/mapb_1990/hTPY7/7/

I use forms designed only with Twitter Bootstrap 3. I set defaults functions for validor and run only validate method with rules. I use Icons from FontAweSome, but you can use Glyphicons as in doc example.

jQuery.validator.setDefaults({
    highlight: function (element, errorClass, validClass) {
        if (element.type === "radio") {
            this.findByName(element.name).addClass(errorClass).removeClass(validClass);
        } else {
            $(element).closest('.form-group').removeClass('has-success has-feedback').addClass('has-error has-feedback');
            $(element).closest('.form-group').find('i.fa').remove();
            $(element).closest('.form-group').append('<i class="fa fa-exclamation fa-lg form-control-feedback"></i>');
        }
    },
    unhighlight: function (element, errorClass, validClass) {
        if (element.type === "radio") {
            this.findByName(element.name).removeClass(errorClass).addClass(validClass);
        } else {
            $(element).closest('.form-group').removeClass('has-error has-feedback').addClass('has-success has-feedback');
            $(element).closest('.form-group').find('i.fa').remove();
            $(element).closest('.form-group').append('<i class="fa fa-check fa-lg form-control-feedback"></i>');
        }
    }
});

Done. After run validate function:

$("#default-register-user").validate({
    rules: {
        'login': {
            required: true,
            minlength: 5,
            maxlength: 20
        },
        'email': {
            required: true,
            email: true,
            minlength: 5,
            maxlength: 100
        },
        'password': {
            required: true,
            minlength: 6,
            maxlength: 25
        },
        'confirmpassword': {
            required: true,
            minlength: 5,
            maxlength: 25,
            equalTo: "#password"
        }
    }
});

JSFiddle example