A pop-up is usually a small window that appears in front of the original web page.

It is a graphical user interface(GUI) display area. The pop-up window opens on the single or double click and can be occured in a particular time period.

The size of the pop-up window must be smaller than the original window. Pop-up is used to add interactive effects.

Below is the example of Custom pop-up:-

HTML-

Here is the HTML for the custom popup, you can change it according to your need.

<a class="btn" id="popup_open" href="#">Click to open popUp</a>
		<div class="popup" data-popup="popup-1">
		    <div class="popup-inner">
		        <h2>Custom PopUp</h2>
		        <p>Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged.</p>
		        <a class="popup-close" id="popup_close" href="#">x</a>
		    </div>
		</div>

CSS-

Below is the CSS for the pop-up.

.btn{
  	background-color: #FF5050;
  	color: #fff;
  }
  .popup {
    width:100%;
    height:100%;
    display:none;
    position:fixed;
    top:0px;
    left:0px;
    background:rgba(0,0,0,0.75);
}
.popup-inner {
    max-width:700px;
    width:90%;
    padding:40px;
    position:absolute;
    top:50%;
    left:50%;
    -webkit-transform:translate(-50%, -50%);
    transform:translate(-50%, -50%);
    box-shadow:0px 2px 6px rgba(0,0,0,1);
    border-radius:3px;
    background:#fff;
}
.popup-close {
    width:30px;
    height:30px;
    padding-top:4px;
    display:inline-block;
    position:absolute;
    top:0px;
    right:0px;
    border-radius:1000px;
    background:rgba(0,0,0,0.8);
    font-size:20px;
    text-align:center;
    line-height:100%;
    color:#fff;
}

JAVASCRIPT-

On click of a button the popup is opened using jQuery.

$(function() {
    $('#popup_open').on('click', function(e)  {
            $(".popup").show().fadeIn('fast');
        e.preventDefault();
    });
    $('#popup_close').on('click', function(e)  {
           $(".popup").show().fadeOut(350);
        e.preventDefault();
    });
});

We can test the popup in below link-

https://jsfiddle.net/z4x3r84r/