As practice for a very difficult upcoming paper, I'm going to practice my skill of definition on an issue I believe is not so much a problem in the way that world hunger is a problem, but a problem specific to artists.
The "animated" picture.
Firstly, the lose definition of animation is a picture of any content that physically moves within the contents of its boarders, no matter what those boarders may be. Whether it's an animated gif of your character doing cartwheels in the snow, or simple colored lines dancing around on your home page, any piece of art that moves is considered animation.
I believe that, as artists, we should strive to work ourselves up every single day and never take the shortest or easiest path. That being said, is a character simply bobbing up and down on their knees "animation?" Now, I will not tell you that it is not animation, but I will tell you that I believe it is a lazy cop-out. My reasons why are simple, it is not challenging, interesting, or accurate. I will seek to explain my reasoning completely
1. It is not challenging
I do not believe every artist has to push their limits for every picture they make, but this is a technique I believe that more experienced artists should, or even need to avoid. Showing your character simply standing in empty space, bobbing up and down at the knees is not helping your technique. For someone who has never tried to animate before, this may be a gateway to gaining the skills they need to make short clips, then episodes, and maybe even movies! But for well-established artists, it's quite disappointing to see. Which leads me to my next point.
2. It is not interesting
Seeing your character bobbing in space is boring. Boring, boring, boring. I looked through an artist's gallery a few days ago and saw that she had made incredible artwork that completely filled her gallery. But I kid you not, every time she advertised an "animation," it was A gorgeously drawn character ... floating in space, and bobbing on her legs. Every animation. I still love her gallery, and I even watched her, but I never added a single animation she made to my favorites because they were so uninteresting. And not to mention they were almost always inaccurate.
3. It is usually not accurate
So what do I mean by inaccurate? It's just a charactering bending their knees, right? How do you get that wrong? Well, they aren't actually bending their knees most of the time, they are snapping them. The fastest and laziest way an artist can make their character bob is by simply selecting the character above the knees, moving them down a bit, and then moving the section back up. The character never bends their knees, they collapse them! Now isn't that a scary thought? It would sure make sense if your character were a shape-shifter or was made of jelly, but for most of these animations that is not the case. You have to understand that humans bust bend our knees to bob, and if your character is not bobbing with the knees and is instead standing on their toes, you still have to elongate the feet to show that. This can be looked over a lot, simply because if something is interesting enough (like the works of Pablo Picasso or Salvador Dali), then it can captivate the beholder. Art is personal and subjective, not one person can say what is or isn't art, and it is not my privilege to argue that.
While a character bobbing up and down is certainly an animation, they are poor examples of animation based solely on the quality of motion. Show us how your character walks, show them doing every day tasks, or show them doing something silly or crazy! Give yourself a challenge; roughly sketch a wire figure doing back flips, try animating a dance move from your favorite music video by hand, or even take a while to study how the hands or feet can move. You can always benefit from practice, even when you think you are doing well already. I learn something new about art every day, and I will continue to do so and improve my talent because of it. Please do not let this review deter you from practicing animation. My intent was simply to help already established artists improve upon their skills by providing a critique of this type of animation.