A quick definition of general improvement:

General Improvement: An addition to a piece of land or property that makes it better or more useful. This can include things like adding a new building or making repairs to an existing one. A general improvement can benefit the public as a whole, or just the people who own the property. Some improvements, like sidewalks or sewers, are paid for by special assessments on nearby property owners. Others, like adding a new room to a house, are made by the owner themselves. A valuable improvement is one that adds permanent value to the property, while a necessary improvement is made to prevent the property from getting worse.