HTML
<form name="my_form" id="my_form" accept-charset="multipart/form-data" onsubmit="return false">
    <input id="name" name="name" placeholder="Enter Name" type="text" value="">
    <textarea id="detail" name="detail" placeholder="Enter Detail"></textarea>
    <select name="gender" id="gender">
        <option value="male" selected="selected">Male</option>
        <option value="female">Female</option>
    </select>
    <input type="file" id="my_images" name="my_images" multiple="" accept="image/x-png,image/gif,image/jpeg"/>
</form>
JavaScript
var data = new FormData();
//Form data
var form_data = $('#my_form').serializeArray();
$.each(form_data, function (key, input) {
    data.append(input.name, input.value);
});
//File data
var file_data = $('input[name="my_images"]')[0].files;
for (var i = 0; i < file_data.length; i++) {
    data.append("my_images[]", file_data[i]);
}
//Custom data
data.append('key', 'value');
$.ajax({
    url: "URL",
    method: "post",
    processData: false,
    contentType: false,
    data: data,
    success: function (data) {
        //success
    },
    error: function (e) {
        //error
    }
});
PHP
<?php
    echo '<pre>';
    print_r($_POST);
    print_r($_FILES);
    echo '</pre>';
    die();
?>