Array Modifier
Select object you want to apply modifier, then add array component. (Modifiers->Array->[Type]).

General Settings
- Type: Type of array
- Count: Size of array
- Dimensions: Dimension array
- Components changed: Update array when components of original object changed
Linear
- Constant:
- Offset: Offset of clones in array in units of Unity
- Rotate: Rotation of clones in world space
- Scale: Scale of clones in world units
- Relative:
- Object: Base object for calculate the displacement / rotation / scaling
- Offset: Offset of clones in array in units of Object
- Rotate: Rotation of clones in Object space
- Scale: Scale of clones in Object units
Circle
- Radius: Circle radius
- Direction radius: Direction of radius (from original object to center of circle)
- Rotation axis: Axis around which build circle
- Use rotation: use rotation for clones
Curve
- Curve color: Color of curve
- Distance: Distance between clones
- Allow count: Uniform distribution of objects along the entire length
Object
- Object: Transform used for create the array
- Use offset/rotation/scale: Use offset/rotation/scale for clones