Cinema has always been a major part of our entertainment. Initiated from a monochrome video clip, to now a full VFX movie; this has been the history of world cinema. This trend broke the ceiling when Pixar released the Toy Story in 1995A.D. which the first fully animated movie. Though before that, other movie too featured some VFX but Toy Story was the first 3D animated movie. And then, this trend went on. One by one, Hollywood gave us many movie which were highly CG( Computer Generated) dependent. But all these actions we see, all the aliens we observe and all those wars where we were virtually indulged doesn't easily come up from the computer. Years of compositing and hard-work finally lead to the "awesome" movie. All the movies that we watch now, whether that be Iron Man, Justice League or Interstellar, they all follow the same way. So being enthusiast of both cinema and computer, here I'm gonna share some of my knowledge about the type/aspects of today's movies' visual effects.
It simply means putting together different stock footage/images to build up a sequence. For instance, a simple explosion scene can be created adding a stock footage. Chroma key is it's major pillar.
#2: 3D Animation.
Movies like COCO and The Ramp, are the examples of 3D animation. It is quite a complex thing to do. And, it has inter-components like texturing, rigging, tracking and way more.
#3: 2D Animation or Stop Motion.
It is the process where still images/photos are compiled together to create a movement. The cartoons, i.e Ninja Hattori, Shaun the sheep, are it's examples.
#4: Digital Art.
It includes the digital painting, pictures or designing. Matte Painting is it's example. Also, it has a great role in game designing.
All these come together and make a great movie. Not an expert but my knowledge in this regard mentions the above point. Some may call them as special effects, or animation or CGI ( Computer Generated Images ) or VFX, but all of them are included within the category of visual effects. Not only movies but today many series are dependent upon it. Game of thrones, Gotham are the excellent examples for this. Ultimately, without visual effects, today's movies would be completely monotonous.