Digger is a military slang term for primarily infantry soldiers from Australia and New Zealand. Evidence of its use has been found in those countries as early as the 1850s, but its current usage in a military context did not become prominent until World War I, when Australian and New Zealand troops began using it on the Western Front around 1916–17. Evolving out of its usage during the war, the term has been linked to the concept of the Anzac legend, but within a wider social context, it is linked to the concept of "egalitarian mateship".

Mateship is an Australian cultural idiom that embodies equality, loyalty and friendship. Russel Ward, in The Australian Legend (1958), once saw the concept as central to the Australian people. Mateship derives from mate, meaning friend, commonly used in Australia as an amicable form of address.