How to make smooth circles in Photoshop without jagged edges

I tried numerous times to make a smooth circle, but I kept ending up with jagged edges in Photoshop. I knew I had been missing something and that's what kept spoiling my design. I then realized - hey, unlike Illustrator, Photoshop isn't a Vector tool. It is a Raster tool. But there must be something I could do to get a perfect smooth circle. And this did the trick:

For circular shapes:

• Select the Ellipse Tool
• On the top panel, change the mode from Shape to Pixels. 
• Tick the Anti-alias checkbox.
• Now draw your shape!

For circular selections:

• Select the Elliptical Marquee Tool
• Tick the Anti-alias checkbox.
• Now go ahead and make that selection!

While making selection from a path:

• Make sure that the 'Anti-Aliased' checkbox is ticked.

For a better understanding of the Anti-Alias feature, see the comparison image below (Click to enlarge):

Creating and Saving Paths in Photoshop

When you create a path using a pen tool in Adobe Photoshop CS6, it appears as a work path in the Paths panel. Note that a work path is temporary and unsaved. Also, you can have only one work path at a time.

If the work path is selected when you begin another path, your actions are added to the current work path. If the existing work path is hidden and you begin drawing another path, that new work path replaces the existing one.

Make sure that your path is saved before you start creating it. If you select New Path from the Paths panel pop-up menu before you create the path, Photoshop saves the work path, and it becomes a saved path. You can also click the Create New Path icon at the bottom of the Paths panel.

To save a work path, double-click the path in the Paths panel. Or choose Save Path from the Paths panel pop-up menu. (Click the down arrow in the upper-right of the panel to open the menu.) Then, provide a name in the Save Path dialog box that appears and click OK. You can reuse the path again anytime you wish to.