IPython Notebook has two sets of keyboard shorcuts. Edit mode is active when the cursor is in a cell and the cell has a green border. Command mode is active when the cell has a grey border and the editing cursor is not inside any cell.
Active in Both Modes
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 | Run cell | 
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 | Run cell and select cell below | 
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 | Run cell and insert new cell below | 
| 
 
 | Save notebook | 
Edit Mode
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 | Command mode | 
| 
 | Split Cell | 
Command Mode
| 
 | Go to edit mode | 
| 
 | Switch cell to code mode | 
| 
 | Switch cell to Markdown/LaTeX mode | 
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 | Switch cell to Heading of respective level (1-6) | 
| 
 
 | Go to cell above | 
| 
 
 | Go to cell below | 
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 | Move cell up | 
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 | Move cell down | 
| 
 
 | Extend selection up | 
| 
 
 | Extend selection down | 
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 | Insert cell above | 
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 | Insert cell below | 
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 | Cut cell | 
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 | Copy cell | 
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 | Paste cell below | 
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 | Delete Cell Press twice | 
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 | Undo delete | 
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 | Split cell at cursor | 
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 | Merge with cell below | 
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 | Merge selected cells | 
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 | Toggle line numbers | 
| 
 | Toggle all cell line numbers | 
| 
 
 | Toggle output | 
Kernel
| 
 | Interrupt kernel | 
| 
 | Restart kernel | 
Inspector
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