Guangdong is a coastal province in South China, on the north shore of the South China Sea. with Guangzhou as the capital. With a population of 127.06 million (as of 2023) across a total area of about 179,800 km² (69,400 sq mi), Guangdong is China's most populous province and its 15th-largest by area, as well as the third-most populous country subdivision in the world.

Guangdong's economy is the largest of any provincial-level division in China, with a GDP of CN¥14.16 trillion (US$2.0 trillion in GDP nominal) in 2024, contributing approximately 10.5 percent of mainland China's economic output. It has a diversified economy, and was known as the starting point of ancient China's Maritime Silk Road. It is home to the production facilities and offices of a wide-ranging set of Chinese and foreign corporations. Guangdong has benefited from its proximity to the financial hub of Hong Kong, which it borders to the south. Guangdong also hosts the largest import and export fair in China, the Canton Fair, in Guangzhou. The Pearl River Delta Economic Zone, a Chinese megalopolis, is a core for high tech, manufacturing and international trade. In this zone are two of the four top Chinese cities and the top two Chinese prefecture-level cities by GDP: Guangzhou and Shenzhen, the first special economic zone in the country. These two are among China's most populous and important cities, and have become two of the world's most populous megacities and leading financial centres in the Asia–Pacific region.

Guangdong surpassed Henan and Shandong to become China's most populous province in January 2005, registering 79.1 million permanent residents and 31 million migrants who lived in the province for at least six months of the year; the total population was 126,012,510 in the 2020 Chinese census, accounting for 8.93 percent of mainland China's population. This makes it the most populous first-level administrative subdivision of any country outside South Asia. The vast majority of the historical Guangdong Province is administered by the People's Republic of China (PRC). Pratas Island in the South China Sea is part of Cijin District, Kaohsiung, Taiwan (ROC); the island was part of Guangdong before the Chinese Civil War.

After the unification of Lingnan region during the Qin dynasty, immigrants from the Central Plains moved in and formed a local culture with a unique style. With the outward movement of the Guangdong people, the Cantonese, Hakka and Teochew languages, music, cuisine, opera and tea ceremony have spread throughout the nation, Southeast Asia, and other countries. Guangdong was also the birthplace of the father of modern China and the founder of the Republic of China, Sun Yat-sen. He declared a military government there in the Warlord Era. The two special administrative regions of Hong Kong and Macau fall within the scope of Guangdong's cultural influence, and its culture still has profound influences on the Chinese in Singapore and Malaysia, with the vast majority of the Chinese diaspora in the two countries claiming ancestry from Guangdong.

Guangdong is also one of the leading provinces in research and education in China. It hosts 160 institutions of higher education, ranking first in the South Central China region and second among all Chinese provinces/municipalities, after Jiangsu. As of 2023, two major cities in the province ranked in the world's top 20 cities (Guangzhou 8th and Shenzhen 19th) by scientific research output.

"Guǎng" (traditional Chinese: 廣; simplified Chinese: 广) means "wide" or "vast", and has been associated with the region since the creation of Guang Prefecture in AD 226. The name "Guang" ultimately came from Guangxin (廣信; 广信), an outpost established in Han dynasty near modern Wuzhou, whose name is a reference to an order by Emperor Wu of Han to "widely bestow favors and sow trust". Together, Guangdong and Guangxi are called Loeng gwong (兩廣; 两广; liǎng guǎng) During the Song dynasty, the Two Guangs were formally separated as Guǎngnán Dōnglù (廣南東路; 广南东路; 'East Circuit in Southern Guang') and Guǎngnán Xīlù (廣南西路; 广南西路; 'West Circuit in Southern Guang'), which became abbreviated as Guǎngdōng Lù (廣東路; 广东路) and Guǎngxī Lù (廣西路; 广西路).

"Dōng" (traditional Chinese: 東; simplified Chinese: 东) means "east".

"Canton", though etymologically derived from Cantão (the Portuguese transliteration of "Guangdong"), usually by itself refers to the provincial capital Guangzhou. Historically, Canton was also used for the province itself, but often either specified as a province (e.g. Canton Province), or written as Kwangtung in the Wade–Giles system and now most commonly as Guangdong in Pinyin. The local people of the city of Guangzhou (Canton) and their language are called Cantonese in English. Because of the prestige of Canton and its accent, Cantonese can also be used, in a wider sense, for the phylogenetically related residents and Chinese dialects outside the provincial capital.^{[citation needed]}