Move Tool: Allows you to move a selection or entire layer by dragging it with your mouse or using your keyboard arrow keys
Marquee: Allows you to select rectangular, elliptical, single column or row of your image.
Lasso: Allows you to select precise areas of an image by drawing or tracing the selection outline.
Quick Selection/Magic Wand: Select and area of an image based on its colour.
Crop: Allows you to select an area of an image and discard everything else.
Eyedropper: Picks up a colour.
Healing, Patch, Red Eye Reduction: Allows you to fix image imperfections.
Bruch, Pencil: Allows you to paint and draw.
Clone Stamp: Allows you to duplicate part of an image.
Eraser: Erases part of the image.
Gradient: Very useful for creating masks
Blur, Smudge, Sharpen: B, S, S areas of you image.
Dodge, Burn, Sponge: Lighten or darken areas which are under or over exposed. Saturate or desaturate colour.
Pen: Draw accurate shapes, select them, fill them or outline them.
Text: Add text.
Path/Direct Selection Tool: Select part or all of a path.
Shape: Draw rectangles, ellipses and polygons.
Hand, Rotate View: Move your canvas around the screen or rotate your canvas.
Zoom: Zoom in or out (hold Alt key)
Colour: set foreground and background colour.
Quick Mask: make a quick selection for a mask.