I often see posts with both tags, but what is the clear difference? Also, is it correct?

drag007 said:
I often see posts with both tags, but what is the clear difference? Also, is it correct?

In principle, transparent border describes a border surrounding an image, which is transparent such that the underlying webpage appears through the border. A great example of this is post #2897077. The background is pink, but a transparent border exists around the background so that portions of the dominant character's legs and tail appear directly over the webpage background. Note that it would still be a transparent border even if no part of the character's body were occluding the border, as in post #3531986. The transparent border exists here so that the artist can give the background of the picture a rounded edge on the corners.

In contrast, transparent background describes a background which is transparent, as in post #1779625. Note that the wiki page for alpha channel states that transparent_background should be used only when the entire background is transparent. Otherwise, you should use the tag alpha_channel.

It appears that a number of recent submissions have been incorrectly tagged; they should be tagged transparent_background, because the entire background is transparent, yet they have instead been tagged transparent_border. Additionally, there is no clear guidance at present on how to tag images with a semi-opaque (i.e., translucent) border, such as post #3558597 or post #1148504. Transparent_border implicates alpha channel, which means that images in which the border shows the underlying background should not be tagged with transparent_border, as there is no use of the alpha channel. The border just shows some of the background underneath, rather than being transparent to show the webpage behind the image.

In summary:

• transparent_border means the image has a border with a transparency effect, to show the webpage underneath. Examples: post #2897077, post #3531986
• transparent_background means that more than just the border is transparent; the entire background is transparent. Example: post #1779625
• alpha_channel means that there are transparent elements of the image, whether it's part of the character, the background, a border, or anything else. This tag applies to all images which use transparency, even if it isn't an entire border or background that is transparent. Examples: post #2022846, post #1276459
• There is currently no tag for when a semi-transparent border shows the background of the image underneath the border. Examples: post #3558597, post #1148504

EDIT: I added a little more explanation and a few more examples. If it is still unclear, please let me know and I can explain further. :)