DynamicWrapper[e, expr] represents an object that displays as e, but dynamically updates the expression expr whenever that object is visible on screen.

ExtentElementFunction is an option to DiscretePlot and DiscretePlot3D that gives a function to use to generate the primitives for rendering each extent element.

InterpretationBox[boxes, expr] is a low-level box construct that displays as boxes but is interpreted on input as expr.

StringLength["string"] gives the number of characters in a string.

TagBox[boxes, tag] is a low-level box construct that displays as boxes but maintains tag to guide the interpretation of boxes on input.

TopologicalSort[g] gives a list of vertices of g in topologically sorted order for a directed acyclic graph g.

WaveletScale is an option for ContinuousWaveletTransform and related constructs used to specify the smallest resolvable scale.

Making lists from functions. This makes a list of 5 elements, each of the form p[i]. Here is another way to produce the same list.

"Interrupting Calculations" describes how you can interrupt a Mathematica computation by pressing appropriate keys on your keyboard. In some cases, you may want to simulate ...

Numerical sums and products. This gives a numerical approximation to ∑_(i=1)^∞((1)/(i^3+i!)). There is no exact result for this sum, so Mathematica leaves it in a symbolic ...