An expression like x^2+2x-7==0 represents an equation in Mathematica. You will often need to solve equations like this, to find out for what values of x they are true. This ...

"CopySpecial" is a front end token that converts the selection to a specified format and copies it to the clipboard.

Automatic Numbering creates an automatic numbering object, or counter, in the current notebook.

Initialization Cell makes a cell auto-evaluate whenever the notebook is opened and the kernel is launched.

Initialization Group makes the cells in a group auto-evaluate whenever the notebook is opened and the kernel is launched.

CellOpen is an option for Cell that specifies whether the contents of a cell should be explicitly displayed.

ControllabilityGramian[ss] gives the controllability Gramian of the StateSpaceModel object ss.

CurrentImage[] returns the current image captured from a connected camera.CurrentImage[n] returns n sequential image frames as a list.

DefaultDuplicateCellStyle is a notebook option that specifies the default style to use for cells created by automatic duplication of other cells in the notebook.

FilePrint["file"] prints out the raw textual contents of file.