One of Photoshop's key features is that almost everything in it can be controlled using keyboard shortcuts. This allows the user to stay in a creative thought pattern and quickly change tools in monotonous work that requires it.
Main Toolbar
Key
Action
Action
Key
m
Marquee Tool 
 Move Tool
v
l
Lasso Tool 
 Magic Wand Tool
w
j
Airbrush Tool 
 Paintbrush Tool
b
s
Rubber Stamp Tool 
 History Brush Tool
y
e
Eraser Tool 
 Pencil Tool
n
r
Blur Tool 
 Dodge Tool
o
p
Pen Tool 
 Type Tool
t
u
Measure Tool 
 Linear Gradient Tool
g
k
Paint Bucket Tool 
 Eyedropper Tool
i
h
Hand Tool 
 Zoom Tool
z
d
Default foreground and background colors.
Switches between foreground and background colors.
x
q
Switches between standard mode or quick mask mode.