IEnumerable . What T stands for?, pls help me out.

hi, usually if we want use Inumerable, we will use follows.
class program
{
static void main(string[] args)
{
List<int> oyears=new List<int>();
oyears.Add(100);
oyears.Add(101);
oyears.Add(102);
}
IEnumerable<int> enum=(IEnumerable<int>) oyears;
foreach(int i in enum)
{
console.wriline(i);
}
output : 
101
102.

here IEnumerable<int> , int is datatype. so What is IEnumerable<T>. here T is What or stands for?..please help me out.

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