The history of an interactive Wolfram Language computation is both maintained in a fully editable Wolfram Language notebook and stored symbolically in a sequence of In and Out objects that can immediately be used in other Wolfram Language commands.

Out (%, %%, %n, ...) — output expressions

In — unevaluated input expressions

InString — original input strings

MessageList — messages produced while generating each output

CellLabel  ▪  ShowCellLabel  ▪  CellLabelAutoDelete

— copy down an input line (Insert ▶ Input from Above)

— copy down an output line (Insert ▶ Output from Above)

InputForm — show output, graphics, etc. in input form

Iconize — make an iconized form of large output

$Line — resettable current line number

$HistoryLength — number of previous outputs to keep

$OutputSizeLimit — maximum size of output to give explicitly

$NotebookInlineStorageLimit — maximum size to include explicitly in compact outputs

Cell ▶ Notebook History — summarize the editing history of a notebook

Saving Session History Information

Save — save definitions for symbols, functions, or contexts

Put, PutAppend — save Wolfram Language expressions

NotebookSave  ▪  NotebookAutoSave

File ▶ Save