The physical structure of the Earth, starting from the center, consists of a solid inner core surrounded by a liquid outer core. The outer core is enveloped by a highly viscous layer called mantle the physical properties of which are equivalent to that of a solid. The outermost layer is called the crust which is solid too and is approximately 6 km thick under the oceans and 50 km thick under the continents. Tectonic plates refer to contiguous segments of the crust that move independently of each other. The motion of the tectonic plates over billions of years has changed the surface of the Earth and led to the formation of the continents and the oceans as we see them today from a single large continent called Pangaea.
The tectonic plates continue to move, though the very slow pace at which they do so compared to how long humans have existed on the Earth gives us an impression that the geographical structure of the Earth is constant. With the help of modern technology like satellite imagery it is possible for geologists to see the present movement of tectonic plates and make very rough estimates of how the Earth would look in the future.
It is estimated that in 30 - 50 millions years, Africa would move towards Europe and the interaction of the two plates lead to the formation of a mountain range like the Himalayan mountain range. The North and South Americas are estimated to move farther away leading to an expansion in the Atlantic Ocean. Australia is estimated to move towards Asia with a formation of a joint continent.