Drought is when you have less rainfall than expected, it usually lasts a month or several.
Droughts can have huge impacts on:
Agriculture, because you don't have enough rain water for the crops to grow.
City water supplies, because there will be a shortage of water to water garden plants or grass, when a drought happens sometimes the residents get told not to use hose pipes and try and to conserve water by only using the smallest amount possible and also to collect rainwater to use for watering plants rather than using tap water. People are advised to do this anyway but more so when there is a drought.
Altohough many people don't think of droughts as being major natural disasters, sometimes they can be extreme and major because we take water for granted and it's a part our everyday life for humans and wildlife and because we don't realise a drought is going to happen until it happens that makes it a serious as there is no 'back-up' and we have to cope with it without any warning.
Although it doesn't hasn't caused fatalities or injuries, it's very costly and a devastating disaster especially to poorer countires that don't have the technology to help people get through it and recover from it.