Iframes are embedded into web pages. You can embed an <iframe> in a page, which is inside another <iframe> on another web page.
To open the link from <iframe> in the parent window, you can use the <base> tag and set the target attribute to _parent in the <head> section.
<!DOCTYPE html>
<html>
<head>
<title>Title of the document</title>
<base href="https://www.w3docs.com/" target="_parent">
</head>
<body>
<iframe src="https://www.w3docs.com" width="500" height="500"></iframe>
</body>
</html>
Now, you can compare the example above with the following one, where the target attribute is set to _blank, which loads the link in a new window.
<!DOCTYPE html>
<html>
<head>
<title>Title of the document</title>
<base href="https://www.w3docs.com/" target="_blank">
</head>
<body>
<iframe src="https://www.w3docs.com" width="500" height="500"></iframe>
</body>
</html>