Herbicides (US: /ˈɜːrbɪsaɪdz/, UK: /ˈhɜːr-/), also commonly known as weedkillers, are substances used to control unwanted plants.[1] Selective herbicides control specific weed species, while leaving the desired crop relatively unharmed, while non-selective herbicides (sometimes called total weedkillers in commercial products) can be used to clear waste ground, industrial and construction sites, railways and railway embankments as they kill all plant material with which they come into contact.