UNCLOS is an international treaty that acts as a legal rulebook for the world's oceans and maritime activities.

An Exclusive Economic Zone is a maritime zone extending up to 200 nautical miles from a country's coast.

Within an Exclusive Economic Zone, a country has sole rights to fish, drill for oil and gas, and manage all natural resources.

An island stays above water at high tide and can sustain life, which grants a country a full 200-nautical-mile Exclusive Economic Zone.

A rock stays above water at high tide but cannot sustain life, granting only a small 12-nautical-mile territorial sea and no Exclusive Economic Zone.

A low-tide elevation is completely submerged at high tide and generates no maritime zones or resource rights at all.

Reefs and shoals are judged by whether they are underwater at high tide, making them either rocks or low-tide elevations.

Legal classification matters because it determines if a country controls thousands of miles of ocean resource wealth or nothing at all.

Building artificial structures on a submerged reef does not change its legal status or create new resource zones under UNCLOS.

The Philippines asked the 2016 tribunal to rule on the legality of China's nine-dash line claim and the status of specific features.

The tribunal decided that China's nine-dash line has no legal basis under international law.

The tribunal decided that all features in the Spratly Islands are legally rocks or low-tide elevations, meaning none of them generate an Exclusive Economic Zone.

The tribunal decided that China violated the Philippines' sovereign rights by interfering with its fishing and oil exploration.

The tribunal did not decide which country has territorial sovereignty or owns the actual land of the disputed features.

China rejects the ruling because it did not consent to the arbitration, claims historic sovereignty over the area, and argues the tribunal lacked jurisdiction over sovereignty disputes. China was one of the original signers of the UNCLOS in 1982, ratified in 1996.

Given the aforementioned information, it is clear that ownership of a "rock, shoal, or island" is valuable not just for the possibility of territorial expansion, but for the mineral rights in the surrounding waters. Not to mention the oil reserves that can be found.

The Spratly Islands are a group of islands, reefs, and shoals in the South China Sea claimed in whole or in part by China, Taiwan, Vietnam, the Philippines, Malaysia, and Brunei.

Second Thomas Shoal is a shallow reef in the Spratly Islands that is occupied by the Philippines through its military personnel stationed on the BRP Sierra Madre.

The Philippines deliberately grounded the BRP Sierra Madre there in 1999 to maintain a permanent military presence and reinforce its claim to the shoal.

The Philippines conducts regular resupply missions to provide the troops aboard the Sierra Madre with food, water, fuel, equipment, and other necessities.

China attempts to interfere with some resupply missions because it opposes the Philippine military presence at Second Thomas Shoal and wants to strengthen its own position in the area.

China has built artificial islands and military facilities on Fiery Cross Reef, Mischief Reef, Subi Reef, Cuarteron Reef, Gaven Reef, Hughes Reef, and Johnson Reef, including runways, ports, radar, and defensive systems.

Runways, radar, ports, and military facilities make tiny reefs strategically valuable by allowing countries to monitor the region, support ships and aircraft, and maintain a permanent military presence.

It is located in the South China Sea. It is 120 nautical miles away from the Philippines. 2. It is claimed by China, Taiwan, and the Philippines. China currently exercises control around it after a conflict with the Philippines. 4. The PCA ruling found that both Filipino and Chinese fishermen have common rights to the territory. 5. There have been multiple military incidents between China and the Philippines, plus US involvement. 6. They are preferred because they allow states to assert control and pressure rivals without political, legal, and military costs. 7. Physical and tactical miscalculation, military escalation, and deployment shifts.