Animation is where still images that are manipulated to create an illusion of movement. If a ball is dropped and you have one photo at the top and one at the bottom it wouldn't look like it moved but if you have 12 still images between it can create the illusion that it is moving!
Animation is used for a variety of things such as: creating videogames, TV shows, movies and so much more! It can also be used for other things that you wouldn't think of such as getting a tour around a proposed house that has been created through somebody digitally creating and designing it! Animation can take on many forms such as the ones I've listed below.
Animation has multiple different types. Such as 2D animation which is used for shows such as Phineas and Ferb, Family Guy, and classic Walt Disney movies such as Beauty and the Beast or Cinderella, it is made by hand-drawn images! 3D animation is also another insanely popular technique and is probably one of the most used variations of this century. Some examples of 3D animation pieces are: Toy Story, Shrek and the Call of Duty franchise, they are created by using 3D assets and putting them into a scene and animating them. Motion capture is also classed as animation and has received a massive boost in the last decade or two. It is widely used in video games and 3D animations and can create more realistic and human-like movements than manually creating the movements. This is achieved by someone wearing a mocap (short for motion capture) suit and the sensors on the suit track the movement and create a skeleton like figure so it easy to then animate it afterwards! They can even be more peculiar forms that you wouldn't think of such as stop-motion, stop motion can be made using anything that you can move so it is easily accessible! You can create a cutout of a bird and place it onto a scene you have drawn on a sheet of paper and take multiple photos but between every photo you take just move the bird along the sheet of paper and when you put it together it looks like it is moving.
There are many famous animation studios that are around present day and some of the most prominent ones are Pixar Animation Studios, Walt Disney Animation Studios, DreamWorks Animation, Cartoon Network Studios and Warner Bros. Animation. They have all released movies/tv shows that have became household names and many people watch their content regularly... including me!
PIXAR is probably the most renowned aniamtion studio. It has created classics such as Toy Story and Cars which saw megastars such as Tom Hanks and Owen Wilson voice act for an animation. The best rated film they've made is Toy Story which was released in 1999 and has a Rotten Tomatoes rating of 100%!
Dreamworks is another insanely popular animation studio that has created cult classics such as Madagascar, Shrek and Flushed Away! Even though How to Train Your Dragon (2010) has a rating of 99%, the rating on average doesn't even compare to Pixar.
Warner Bros. is also a MASSIVE animation company but their ratings don't compare very well to either of the companies listed above. Their highest rated film is The Lego Movie with a rating of 96% but apart from that their rates fall but you still can't deny that they have made some entertaining films.