There are three types of landgrabbing--bottom-feeding, mid-feeding, and top-feeding. How these types of landgrabbing are measured is left entirely up to individuals or alliances. Some may measure based on the amount of land between the attacking country and the defender, while some may measure based on the amount of land between the two countries, while others may measure based on a combination of the two. Still, others may measure based on the amount of land gained or lost from each attack.
Generally, a bottom-feed occurs when a much larger country attacks and gains land from a much smaller country Bottom-feeding generally requires sending a tiny portion of a country's military forces for the attack, but gains a relatively tiny portion of land. The tiny country is usually unable to regain its land through retaliations against the larger country.
Mid-feeding happens when a country attacks a similar country. The two countries may even be the same networth, which usually makes the gains from each attack very lucrative. Assuming the attacker doesn't change networth by too much, the defender could then retaliate against the attacker, and gain a similar amount of land back.
Top-feeding is when a smaller country attacks a much larger country (and usually gains much more land than the defender will be able to gain back on a single retaliation). Top-feeding is generally looked down upon by established alliances who hole fairness in high esteem. They may then vary their retaliations accordingly.
The concept of ghost acres has been around since the old Earth:2025 game. For more information, see ghost acres.