Infinity or \[Infinity] is a symbol that represents a positive infinite quantity.
Infix
(Built-in Mathematica Symbol) Infix[f[e_1, e_2, ...]] prints with f[e_1, e_2, ...] given in default infix form: e_1~f~e_2~f~e_3 .... Infix[expr, h] prints with arguments separated by h: e_1 h e_2 h e_3 ...
Information[symbol] prints information about a symbol.
Inherited represents an option value to be inherited from an enclosing style, cell, or notebook.
InitializationCellEvaluation is an option for notebooks that specifies whether initialization cells in a notebook are automatically evaluated when the notebook is opened.
InitializationCell is an option for Cell that specifies whether the cell should be tagged to be evaluated by the Mathematica kernel when the notebook that contains it is ...
InitializationCellWarning is an option for notebooks that specifies whether a warning should be given when a notebook containing initialization cells is opened.
InitializationGroup is an option for the first cell of a cell group that specifies whether the group should be tagged to be evaluated by the Mathematica kernel when the ...
Initialization is an option for Dynamic, DynamicModule, Manipulate, and related constructs that specifies an expression to be evaluated when the construct is first used or ...
In
(Built-in Mathematica Symbol) In[n] is a global object that is assigned to have a delayed value of the n\[Null]^th input line.