Ideally a stairway should be enough to allow two persons to pass each other, a minimum of 36 "wide, 34" high.
The newel is the main post where the stairs begin and end also where the landing junctions occur.
The balusters, also called spindles, connect the tread to the handrail. Make sure that the distance between each baluster is no more than 4 "maximum. More than 4" is against code and could allow a child's head to get caught.
The handrail is the rail that is parallel to the slope of the stringer from newel post to newel post.
The landing is the platform between straight runs of steps in an L-shaped or U-shaped stairway.
Some information about building stairs.
The riser is the distance from the top of the step to the next step, usually anywhere from 6 "to 8" high. (8 1/4 "maximum).
The tread is the step itself that you step on, usually 9 "to 12" wide.
When you add the riser and the tread together it should be between 17 "to 21" with 18 "to 19" being your average.
The stringer is the carriage that supports the treads and the risers, usually a 2 "x 12" or 2 "x 10" cut to fit the steps.
How to figure the steps: Measure the distance from the floor or ground to the top of your landing, top of deck or the next floor.
Example: If the distance from the ground to the top of the deck is 45 "high, you divide by 7" or 8 "to find how high each step will be.
In this case we find that 71/2 "will be the height of each step, which means that you will have 6 risers and 5 treads.
To cut your stringer, take your square and place it on the edge of your stringer to read 71/2 "on one side and 11" on the other side of the square; (11 "for using a 2" x 12 "or 2- 5/4 x 6" deck boards). Draw 5 steps with 6 risers. Cut off the thickness off your bottom riser 1 "or 1 1/2" to allow a 7 1/2 "total. You are now ready to assemble your stairs. Also allow 1 "- 1 1/4" of tread to extend beyond risers as nosing for treads. You may want to practice on an old board if you are not sure. Or you can buy the pre-made stringers at the lumber yard, but you do not have the option to choose the height of your risers.
A deck that is 32 "or less does not needarily need railings by code. (check with your local authority)