What is a thumbnail
Thumbnail is reduced-size of a picture or video . Thumbnail is used to help in recognize and organize the content as well as them reduce the page load. It serves the same role for images as a normal text index does for words. Thumbnail word is the combination of two words ,thumb and nail .
Uses And Working
Thumbnails are also play great role to increase traffic of a website . Because of all of visual search engines such as google images are use thumbnails to index or recognize the content and display it .
On the other hand modern operating systems such as Microsoft Windows, Mac OS X, KDE (Linux) and GNOME (Linux) use them to organize and display the content.
Thumbnails are implemented on web pages in separate folder. Smaller copies of the original image.It helps to reduce the page load as well as reduce the bandwidth . Because small images as also small in size (MB or KB) rather than the main big size images.
Displaying a significant part of the picture instead of the full frame can allow the use of a smaller thumbnail while maintaining recognizability.
For example, when thumbnailing a full-body portrait of a person, it may be better to show the face slightly reduced than an indistinct figure. However, this may mislead the viewer about what the image contains, so is more suited to artistic presentations than searching or catalogue browsing.
Standard Size of thumbnail
Now, at present you are thinking that what is the standard size of a thumbnail image. And the answer is that ,there is no standard size . Size is depend of the usage of the image and the platform where the image is displayed . Such as for youtube videos thumb standard size is “1280 pixel x 720 pixel” but for a blog most normal thumbnail size around “200 px x 200 px” .