Selection tool are used to select a portion of image. With this portion allocated (selected) you can do what you want without affecting rest of picture.
See related link for detailed explanation with snapshots.
the masking tool
You can use the pen tool, quick selection tool and lasso.
To crop a selection in Photoshop, use the Crop Tool to draw a selection around the area you want to keep. Then, press Enter or click the checkmark icon to apply the crop.
Selections tools inside Adobe Photoshop are : Lasso tools, Marquee tools, Magic Wand and Quick Selection, Color Range from Select menu and you can also trace edges with Pen Tool or Magnetic Pen Tool which is accessible when Freeform Pen Tool is active.
There isn't drag tool in any Photoshop version. To move things around you can use Move Tool or Path and Direct Selection tools to move paths and shapes.
Using selection tools from Toolbox: Magic Wand, Quick Selection tool, Rectangular and Elliptical Marquee tools...
Quick Selection Tool creates selections by automaticaly detecting edges based on color and texture similarity of surounding pixels with clicked point. You can click or click and drag to create selection with Quick Selection Tool.
magic wand tool, quick selection tool, lasso tool polygonal or magnetic lasso tool. there the main one's.
Selection tools in Photoshop: Marquee Tools (M), Lasso Tools (L), Magic Wand and Quick selection (W). You can also select color from image as foreground or background color with Eyedropper Tool (I). Navigate with mouse above any tool in Photoshop and you will see tooltip with keyboard shortcut for that tool in parentheses.
To use the freeform crop tool in Photoshop to create a custom-shaped selection for an image, simply select the tool from the toolbar, then click and drag to draw a shape around the area you want to crop. Release the mouse button to finalize the selection, then press Enter to apply the crop.
For selections you can your the Marquee Tool, Lasso Tool, or Magic Wand Tool. To cut that selection you can use the Move Tool, or the Ctr-X keyboard shortcut.
To make a color-based selection in Photoshop, you can use the "Magic Wand" tool or the "Color Range" tool. The Magic Wand tool selects pixels of similar color with a single click, while the Color Range tool allows you to select specific colors or tones within an image. You can adjust the tolerance level to refine your selection and then apply edits or adjustments to the selected area.