Overgrazing occurs when plants are exposed to intensive grazing for extended periods of time, or without sufficient recovery periods. It can be caused by either livestock in poorly managed agricultural applications, or by overpopulations of native or non-native wild animals.

Overgrazing reduces the usefulness, productivity, and biodiversity of the land and is one cause of desertification and erosion. Overgrazing is also seen as a cause of the spread of invasive species of non-native plants and of weeds.

Overgrazing is used as the canonical example of the Tragedy of the commons.Sustainable grassland production is based on grass and grassland management, land management, animal management, and livestock marketing. Grazing management, with sustainable agriculture and agroecology practices, is the foundation of grassland-based livestock production since it affects both animal and plant health and productivity.

Overgrazing can occur under continuous or rotational grazing. It can be caused by having too many animals on the farm or by not properly controlling their grazing activity. Overgrazing reduces palatable plant leaf areas, which reduces interception of sunlight and plant growth. Plants become weakened and have reduced root length, and potentially the pasture sod can be weakened although in many locales overgrazing results in an increased sod vigour dominated by unpalatable grasses. The reduced root length makes the plants more susceptible to death during dry weather. A weakened sod allows weed seeds to germinate and grow.^{[citation needed]}

Follow-on is a term used in the sport of cricket to describe a situation where the team that bats second is forced to take its second batting innings immediately after its first, because the team was not able to get close enough (within 200 runs for a five-day match) to the score achieved by the first team batting in the first innings. It is applicable only in the longer (more traditional) two-innings-each match.

If the second team to bat scores substantially fewer runs than the first team, the first team can enforce (at their captain's discretion) the follow-on, instructing the second team to bat again immediately. In this case the sequence of batting innings will be first team, second team, second team and then (if needed) first team, so the second team is said to be "following on". This is in contrast to the normal progression of batting innings which is first team, second team, first team, second team.

This rules governing the circumstances in which follow-on may be enforced are found in Law 13 of the Laws of cricket.