District 4 is one of the 16 Districts of Panem ruled over by the Capitol. District 4's main focus is fishing. This happens to include fish, crabs, shellfish, and other types of seafood. They are one of the better off Districts and have a pretty good relationship wiith the Capitol.
Like Districts 1, 2 and 14, District 4 happens to be a Career District. The Careers from here are often highly skilled in water combat, along with having extensive knowledge of using nets and tridents, making fishhooks from scratch, swimming, and identifying edible sea life.
Unlike some of the other Districts, the jobs in District 4 start at a young age, from fishing to net making, usually giving the tributes from 4 an edge in their Games.