Ruby : `&:symbol` syntax

Question

Possible Duplicate:
Ruby/Ruby on Rails ampersand colon shortcut

Seen in Railscast #167 :

def tag_names
    @tag_names || tags.map(&:name).join(' ')
end

What is this &:name syntax, what does it do ?

I understand what a symbol is, but what other kinds of objects this & can be prepended to ?

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Duplicate question : Ruby ampersand colon shortcut