Purposes of external linksMain purposes of external links are
- Provide ways for the viewers to legally purchase or download the albums or songs.
- Provide ways for the viewers to find out more about the artists or albums.
- Provide points of reference for the information in the database.
The first two points should be obvious. VocaDB is not intented to provide all the possible information about artists, nor can the users buy albums on VocaDB. Artists' own websites, online stores and sometimes other wikis are better for explaining this.
The third point means that links to reliable reference sites, such as vgmdb, Discogs, Hatsune Miku Wiki and the Vocaloid wiki are encouraged. As long as the linked sites are reliable, having more links to such sites makes the information on VocaDB more trustworthy as well. The other sites might still have some useful information that's not on VocaDB. Links to official sources such as artists' website are of course even better, but having multiple references is a good thing.
Do not remove external links, unless the links are dead, the information on the linked site is clearly wrong, or the links violate the VocaDB guidelines.
Sometimes it's useful to keep links that are dead (not working anymore). They can still be used to search for the entry, and link things together.
Most importantly, links to Twitter, YouTube and Nico Nico should be kept even when dead.
Email addresses as linksSome artists share their email addresses publicly for example on their NicoNico profile. These email addresses are not considered very useful information on VocaDB, so adding those is discouraged, although not forbidden. Most of the time such public addresses are so full of spam that the artists have abandoned them anyway.
Forbidden linksDirect download links to files (for example .mp3 or .flac) are not allowed, even if they're legal. Instead, you should always link to the artist's page if possible, be that piapro or some blog. There are multiple reasons for this, but the most important being that this way the artist gets traffic for the downloads.
Links to sites whose main purpose is illegal file sharing are not allowed.