input line. 
In
In[n]
is a global object that is assigned to have a delayed value of the n
input line.
input line to be reevaluated. Examples
open all close allScope (1)
Applications (1)
Reevaluate the third input 4 more times:
Evaluate DownValues for In to see what inputs are stored in this session:
Get the same data using Information. Here this only includes definitions from this example:
Properties & Relations (3)
Referencing an input number greater than the total number of inputs returns unevaluated:
If $HistoryLength is finite, only the $HistoryLength-1 most recent values of In have a value:
The value of $Line corresponds to the numbers in In and Out:
Text
Wolfram Research (1988), In, Wolfram Language function, https://reference.wolfram.com/language/ref/In.html.
CMS
Wolfram Language. 1988. "In." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/In.html.
APA
Wolfram Language. (1988). In. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/In.html