There are many different ways to create animation, there are many softwares such as Flash Player and adobe after effects. Animation thats seen online is mostly posted on youtube where everyone can view it, the animation comes in many formats such as 2D animations, and some even do voice dubs of drawn comics and post them online, there are also web comics, gifs, motion comics and many other things. an example of an online animated series is "cyanide and happiness" on youtube that do little animated sketches that are 2D. The technologies used such as Flash Player and Adobe can make work look different and also ones especially made for 2D animation, the difference between Adobe and Flash Player is that ones made for more advanced animations such as anime or cartoons that are 3D and flash player is focused more on 2D. There are gifs and web comics that people can make using these softwares, also they can be used to make 2D online games. Animated banners are used in ways such as advertising companies or even games and are posted on online websites for people to see. Animated banners are mostly very simple and cartoony nothing over complicated.
Issues that people can encounter while uploading things online like animation could be that it could crash or if you are making a motion comic on a website the site could crash and all work could be lost along with the process. File formats could also cause an issue to uploading it as it could appear awfully on a phone if its not done in he right format, some issues with compression could also occur. When you save an image for example using a format like JPG because its really common, some data is lost because the file is compressed. the JPG files can be saved at various quality settings. the lower the quality % the higher the compression rate. Gifs ( Graphics Interchange Format) its like a JPG the GIF file is format is commonly used on the internet for entertainment, it is an ideal for images that have large blocks of a single color and it can support about 250 colors unlike a JPG and its most likely that the background of a GIF is transparent, which makes it more easier to place over it with other images or place it on a webpage.
Most common softwares for animating series for youtube or to be posted online as videos is Flash Player mainly aimed at 2D and for 3D it could be specific softwares for anime than regular cartoons such as "adventure time" which could be done over Adobe Photoshop and After effects and then they save it as a different format so that people can view these,most files for animation should be saved as HTM5. Types of formats can very from JPG to GIF, MNG, SWF etc
This is a gif and an animated video, the gifs were probably made on Photoshop or any Adobe software. the video of a short animated series episode can have problems such as low resolution and it would take a while to load making the viewer click away and watch something else, gifs on the other hand are quick and memorable and its easy to make them and they load faster than a video. The video of the animation was most likely made over Flash player as its 2D an din color. The pros and cons of a short 5min animated 2D video is that its bright and colorful which is appealing to the eye, its simple to make, can appeal to many audiences as it can contain adult comedy but keep the simple style, the bad things about it is that it could take a while to upload as theres a lot of content that goes into the short video and some editing and frames which can sometimes turn bad or buffer online. The gif is easy to see and can be viewed on any platform and mostly its clear and simple. It doesn't have issues loading as much as videos as it doesn't contain anything and its a loop of the same frames.
This is an example of an animated banner this is usually on corners of websites and easily noticeable and also they do animated advertisement such as children's movies etc.
my sources:
http://www.bbc.co.uk/schools/gcsebitesize/dida/graphics/selectingrev6.shtml
https://www.youtube.com/watch?v=4oLCE4I5IVU
http://iruntheinternet.com/05796
https://www.google.co.uk/search?q=bus+advertising&safe=strict&source=lnms&tbm=isch&sa=X&ved=0ahUKEwju4s_FqtjSAhWEJMAKHVhZBsgQ_AUIBigB&biw=2560&bih=1301#safe=strict&tbm=isch&q=animated+banners+&*
