There are quite a few ways to make selections in Photoshop through several different selection features. Selections play a critical role, because without them we have no way to define an area to select to change in the images you're working on, which is usually a big part of any kind of photo manipulation. Making your selections accurately with a high level of control is extremely important in Photoshop.
I've outlined the tools that are available to you to make selections below.
The first selection tool available is the Marquee tool.
The Marquee tool is just a way of dividing some sort of area that all the other tools in Photoshop can affect.
The first option available is the Rectangular Marquee Tool. When drawing a Marquee, as long as you're holding the mouse button, you can hold Shift while dragging will let you draw out a perfect square. While still pressing and holding on the mouse button if you also press and hold the space bar you'll be able to move your selection to a different part of the image without having to start over.
If you've already drawn a marquee and you press and hold Shift then you'll be able to draw more marquee selections. If you press and hold Ctrl you can remove a selection from your marquee.
When the marquee tool is still active you can click and drag inside of it to move your selection. This will only work if you're still on the selection tool. If you've switched to the move tool then the pixels you've selected with your Marquee tool will move, like in the image below.
The Elliptical Marquee Tool works just like the Rectangular Marquee Tool, with the exception that it creates ellipses. If you'd like to create a perfect circle, you'd do it the same way that you'd create a perfect square with the Rectangular Marquee Tool – by holding down Shift as you drag.
Lasso tools make it simple to make a more accurate selection. There are three different lasso tools available, the Lasso, Polygonal Lasso and the Magnetic Lasso.
With the Lasso Tool all you need to do is click and drag to draw a selection. Once you have selected what you want, just bring back your selection to the starting point. If you don't go back to the place where you started your selection, then Photoshop will automatically connect where you ended to where you started in the most direct way, a straight line.
Making a precision selection is difficult with the Lasso Tool, however, because it'll move quickly.
The Polygonal Lasso will let you draw out different lines by simply left-clicking. There's no need to click and drag. You'll have to make sure you close your selection by clicking back at the start point. If you're ready to make your last click and you press and hold Ctrl then Photoshop will add the last anchor point and close your selection for you.
Maybe you made a mistake and you want to go back one anchor point. All you have to do is press backspace you'll be able to "undo" the little anchor points that you've dropped in without having to start over completely. Holding down Shift while using this tool will create 45 degree angles instead of free flowing lines.
The Magnetic Lasso can be difficult to control and there are other tools that will do the job better, but it's still a good idea to know what it does. This tool works best where there's contrast. Just click once and you can drag your cursor and the Magnetic Lasso will add anchor points around what it thinks are the edges or you can click to add anchor points. You can change the frequency of how often the anchor points are added as well.
Quick Selection and Magic Wand
The Magic Wand tool is good for making large selections. It looks for different things, like variations in color, to help make the selection. The Magic Wand will only make selections on the layer that's currently active, unless you tell it to Sample All Layers by clicking the check box in the tool bar.
Also, if Contiguous is disabled, the Magic Wand will select all of the same color in the image, not just where you've clicked. In the Image below I've clicked a green color and this is the selection that Photoshop made.
If you press and hold Shift you can add to your selection when you click somewhere else. You're also able to change the Tolerance to pick up the color change. If the number is set to "1" then the color tolerance will be very strict. The higher the number, the more forgiving it will be.
The Magic Wand tool is best for more simple situations. If you need to make a better selection, use the Quick Selection Tool. The Quick Select tool, like its name suggests, makes quick selection. You can just click and drag around a layer that you want to select. It'll even work well around areas that don't have a lot of contrast.
The Quick Selection Tool is powerful and can make great selections. I've used the Quick Selection tool in the image below.
It's also possible for you to change your brush size to get the selection that you need just perfect. If there are areas that you don't want selected you can simply hold the Alt key and you'll be able to erase some of your selection.