To determine the octant in which a point lies, we need to consider the signs of its coordinates. The octants are divided by the positive and negative x, y, and z axes.

Given point: (-1, -2, -3)

The x-coordinate is negative, indicating that the point lies to the left of the origin. The y-coordinate is also negative, indicating that the point lies below the origin. The z-coordinate is also negative, indicating that the point lies behind the origin.

Therefore, the point (-1, -2, -3) lies in the 8th octant.

Explanation:
- Octants: The three-dimensional space is divided into eight octants, similar to how a plane is divided into four quadrants.
- Coordinates: The coordinates of a point in three-dimensional space consist of an x-coordinate, a y-coordinate, and a z-coordinate.
- Signs of coordinates: The signs of the coordinates (positive or negative) indicate the position of the point with respect to the x, y, and z axes.
- Negative coordinates: A negative coordinate indicates that the point lies to the left of the origin along the x-axis, below the origin along the y-axis, or behind the origin along the z-axis.
- Positive coordinates: A positive coordinate indicates that the point lies to the right of the origin along the x-axis, above the origin along the y-axis, or in front of the origin along the z-axis.

In this case, the point (-1, -2, -3) has negative coordinates in all three dimensions, indicating that it lies in the 8th octant.