The first thing you will notice when you enter an Orthodox church is the iconostasis. The Iconostasis divides the worship space into two parts, the nave and the altar.

Transcript:

The first thing you’ll notice when you come in an orthodox church is the iconostasis. This is a screen that stands between the worship space generally, and the altar area, and it is holding icons. In the earliest days, when the first churches were being built, it was just a low rail about knee high. As they began putting icons on the walls and the ceiling and the columns and every available surface, they began putting icons on this low wall as well. It got taller and it got more icons. So this is a typical example of what an iconostasis might look like today. Sometimes they’re more like an open screen or just icons standing on posts. Sometimes it’s a virtual wall that goes up, up, up for many levels many, many layers of icons going upward. The iconostasis divides the worship space into two parts. The large part where the people stand is called the nave. N. A. V. E. It sounds like navel, like a ship, and that word came about because the way the ceilings were built with the tresses. It looked like the hull of a ship. So this is the nave. The other part is called the altar. The whole area is called the altar, not just the altar table. Inside the altar space as well you’ll see there are several tables. There’s a preparation table. There are shelves for holy water and for books and for other things a priest might need. All the implements of worship are kept back there.