Trickle irrigation is the practice of dripping water into soil at very low rates, using outlets placed closed to the plant to ensure targeted application to the root zone. Since the 1950s, trickle irrigation technology has become increasingly advanced and widespread. It is believed that the technique will become still more important with the depletion of existing water resources and the long-term effects of climate change. The present chapter focuses on surface trickle irrigation, presenting a summary of the basic components of the technology, before discussing the main advantages and disadvantages of the technique. Trickle irrigation makes use of water in a highly efficient way, in that it avoids typical causes of water loss and allows poorer-quality water to be used. However, trickle irrigation systems are costly to install and challenging to maintain. There is a need to develop cheaper, small-scale trickle irrigation systems that are better suited to smallholder needs.