What is the meaning of 当仁不让? I was browsing the Chinese internet looking for a bank that supports Mac OS when I came across this site. They list a range of different banks under a range of different headings, the first of which is 当仁不让. 

I've looked it up in my dictionary, but I'm really none the wiser. Can anyone tell me what it means in this context? Where does this expression come from? Thanks!
This idiom comes from the famous book of 《论语》, a book recording the Confucius and his disciples' words. Here is the source:

《论语·卫灵公》：“子曰：‘当仁，不让于师’。”

Explanations:

卫灵公 is the name of a chapter of that book.
In that chapter, you can read this sentence(the 36th) &quot;子曰：‘当仁，不让于师’。“ The Confucius said:&quot; when [you are] facing 仁(see note), you should not be modest to decline to do it,even if your teacher is next to you.(Don't leave it to the teacher. Just do it yourself!).&quot;

note: 仁 is the core values in Confucius's thoughts. Here I suggest you simply understand as &quot;justice, morality,universal love&quot;, since it's hard to explain, especially in a short paragraph.
Today, we use this idiom to say:

when facing something that deserves you doing or undertaking because it conforms to our good values or will benefit someone else, don't be shy to say no.Just do it!

Example dialogue based on some a real dialogue :D :

Ciaocibai: Huang,我在Meta上提名你来做管理员了。Huang, I nominated you as moderator on Meta.
Huang: 谢谢你的好意，不过我担心我做不好，因为我还不熟悉StackExchange的制度和管理员工具。Thanks for your kindness, but I am afraid that I can't be a good moderator,because I am not familiar with the discipline of StackExchange and the moderator tools
Ciaocibai: Huang, 我觉得你应当“当仁不让”. Huang, I think you should not be too shy to be a moderator. Show yourself!

In your case, the owner of that webpage wants to say&quot;the banks are good, and I am glad to list them here and share with you. &quot;.