Evaluate Cells sends the currently selected cells to the kernel for evaluation.
Only cells with the option EvaluatableTrue (normally cells in the Input style) will be evaluated. All other cells will be ignored.
If you currently do not have the appropriate kernel running, it will be started for you (see the Default Kernel and Notebooks Kernel submenus).
A cell may have a private kernel specified (see the Evaluator option), in which the cells you evaluate may be sent to different kernels. The output from multiple kernels will be placed after the corresponding input cells as soon as it is received. This means output from lower cells may be placed before output from higher cells.
Keyboard shortcuts: (Windows); or (Macintosh); (X).
Pressing by itself (in Windows and X) does not evaluate a selection--it produces a line break.