What is the differences between a {...} and a:link{...}?
Are there different usages, and benefits between them?
According to W3C a:link is for not visited, a:visited is for visited, and just a applies to both.
a covers all the bases. a:link is used only if the link in un-visited, un-hovered, and in-active.
So, use a for things like font-family (if you want links to come up in a different font), then use link for the standard formatting, and visited, hover and active for 'special effects'.
EDIT: After reading Sander's W3C link, I can see that I didn't have it quite right. a:link will cascade down to a:hover and a:active, i.e. anything in a:link that is not over-ridden by the dynamic pseudo-classes will also apply to them.
a:link only affects links that have a href attribute basically (if a:visited, a:hover or a:active does not apply)... The main case where I've noticed a difference is that a:link doesn't affect Named Anchors whereas a will. Also, a is the default style if none of the other pseudo classes are defiend.
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来源：https://stackoverflow.com/questions/1922643/a-vs-alink-what-is-the-difference