The first formulations of the Amidah prayer appeared in the 4th century BC - it's one of the oldest prayings today.
Whisper the individual Amidah. This is how Hannah, the mother of the prophet Samuel, prayed for a son after many years of childlessness.
The Amidah (עמידה, "standing") has that name because people say it standing up.
The Amidah is also called Shemoneh Esrei (שמונה עשרה, "eighteen") because at first, the weekday version of the prayer had eighteen blessings.