Ground cover is primarily a term to denote plantings that are low, green, and work to cover large areas of ground without the use of grass lawns or mulched flowerbeds. Most ground covers spread, which can be used to your advantage. English ivy works well on steep hillsides, takes little maintenance but will travel up trees if left unattended over the years. Periwinkle flowers nicely in the spring, and pachysandra spreads but is not overly invasive. You can also mass plant lirope or mondo grass into a type of ground cover. All ground covers help with erosion as they have extensive root systems that help to lock in the soil. Generally speaking most ground covers work well in shady areas which gives you an easy no mowing solution in areas that are difficult to grow grass.