Photoshop/101basics/The Basics/Workspace/menubar/window/tools/selectiontools

Before selecting:

• Shift+Drag: To change the marquee to a square or circle.</li>

• <p align="left">Alt+Drag (Option for Mac): To drag marquee from it's center.</li>
• <p align="left">Alt+Shift+Drag(Option for Mac): To drag selection from it's center and change it to a square.</li>
• <p align="left">Holding downSpacebar:  to change selection position.</li> </ul> <p align="left">After Selecting :
  • Shift+Drag: to add more area to selection.
  • Alt+Drag (Option for Mac): to subtract from selection.
  • Alt+Shift+Drag(Option for Mac): to have intersected area only selected.
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selection in rectangles

selection in ellipses

selection in 1-pixel rows

selection in 1-pixel column

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Tools Options

Move Tool</td>

• Shift: Holding shift while dragging to produce a  45� Movement.
• Alt+Ctrl (Option+Command): It copies and moves the new copied shape at the same time
• Alt+Ctrl+Shift (Option+Command+shift): To copy shape and move it in a 45� Movement.
  
  

to drag selections,

layers and move them to a new place on the image you're working with.

Can also be used to align shapes and layers together.

Lasso Tool</td>

• Shift:  to add more area to selection..
• Alt: to subtract from selection.
• Alt+Shift:to have intersected area only selected.

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Magnetic Lasso: Selection snaps to the edges of  the image that you want to select.

Polygonal: Selection is drawn in straight lines

Lasso: Selection is drawn in a freehand-like method.

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Quick Selection Tool</td>

Used to help in painting, while selecting an area the round brush tip expands and find the edges of the image.

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Magic Wand Tool</td>

• Shift:  to add more area to selection..
• Alt: to subtract from selection.
• Alt+Shift:to have intersected area only selected.

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Selection based on color difference in an area. Can be adjusted by it's tolerance. 

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