A half marathon is a road running event of 21.0975 kilometres (13.1094 mi). It is half the distance of a marathon and usually run on roads. Participation in half marathons has grown steadily. One of the main reasons for this is that it is a challenging distance, but does not require the same level of training that a marathon does.
Writing is a system of linguistic symbols permitting one to transmit and conserve information. Writing appears to have developed between the 7th millennium BC and the 4th millennium BC, first in the form of early mnemonic symbols which became a system of ideograms or pictographs through simplification.
A national park is a park in use for conservation purposes. Often it is a reserve of natural, semi-natural, or developed land that a sovereign state declares or owns. Although individual nations designate their own national parks differently, there is a common idea: the conservation of wild nature for posterity and as a symbol of national pride.