Terrace is a polysemic concept. The term can refer to the open location of a House which is located above the ground level, which allows to observe the landscape. Examples: "tomorrow, I will put the table on the terrace for dinner under the starlit sky", "Mary, just please the terrace help your mother with the cloth", "Tamara bought a House with a garden and a terrace.
The terraces can be used to extend the laundry, make meals in the open air and to sunbathe, and much more. Buildings may also have a terrace, situated on the top floor and the use of which is shared by all owners.
A terrace can be, on the other hand, the space along a restaurant, a bar or a cafe which allows customers to sit outside: "Today, we will settle on the terrace and take a bit of air", "I suggest you a table near the window or, if you prefer, a table on the terrace", "the problem with the terrace, is that servers are taking more time to make the commands".
Finally, an alluvial terrace is a platform that is formed in a valley because a river sediments that are deposited on the edges of the bed in the areas where the slope (and, therefore, the ability to drag water) is less.