I know _blank opens a new tab when used with the anchor tag and also, there are self-defined targets I use when using framesets but I will like to know the difference between _parent, _self, and _top
While these answers are good, IMHO I don't think they fully address the question.
The target attribute in an anchor tag tells the browser the target of the destination of the anchor. They were initially created in order to manipulate and direct anchors to the frame system of document. This was well before CSS came to the aid of HTML developers.
While target="_self" is default by browser and the most common target is target="_blank" which opens the anchor in a new window(which has been redirected to tabs by browser settings usually). The "_parent", "_top" and framename tags are left a mystery to those that aren't familiar with the days of iframe site building as the trend.
target="_self" This opens an anchor in the same frame. What is confusing is that because we generally don't write in frames anymore (and the frame and frameset tags are obsolete in HTML5) people assume this a same window function. Instead if this anchor was nested in frames it would open in a sandbox mode of sorts, meaning only in that frame.
target="_parent" Will open the in the next level up of a frame if they were nested to inside one another
target="_top" This breaks outside of all the frames it is nested in and opens the link as top document in the browser window.
target="framename This was originally deprecated but brought back in HTML5. This will target the exact frame in question. While the name was the proper method that method has been replaced with using the id identifying tag.
<!--Example:-->
<html>
<head>
</head>
<body>
<iframe src="url1" name="A"><p> This my first iframe</p></iframe>
<iframe src="url2" name="B"><p> This my second iframe</p></iframe>
<iframe src="url3" name="C"><p> This my third iframe</p></iframe>
<a href="url4" target="B"></a>
</body>
</html>
Section 6.16 Frame target names in the HTML 4.01 spec defines the meanings, but it is partly outdated. It refers to “windows”, whereas HTML5 drafts more realistically speak about “browsing contexts”, since modern browsers often use tabs instead of windows in this context.
Briefly, _self is the default (current browsing context, i.e. current window or tab), so it is useful only to override a <base target=...> setting. The value _parent refers to the frameset that is the parent of the current frame, whereas _top “breaks out of all frames” and opens the linked document in the entire browser window.
target="_blank"
Opens a new window and show the related data.
target="_self"
Opens the window in the same frame, it means existing window itself.
target="_top"
Opens the linked document in the full body of the window.
target="_parent"
Opens data in the size of parent window.
_blank Opens the link in a new window or tab _self Opens the link in the same frame as it was clicked _parent Opens the link in the parent frame _top Opens the link in the full body of the window
The parent frame of a function evaluation is the environment in which the function was called. It is not necessarily numbered one less than the frame number of the current evaluation, nor is it the environment within which the function was defined.
target="_blank" To the new page with blank target="_self" Recall to itself target="_top" Go to the top of document(page) target="_parent" opent the data to it upper tag size
来源：https://stackoverflow.com/questions/18470097/difference-between-self-top-and-parent-in-the-anchor-tag-target-attribute