These are examples.

	cities Seoul, New York, Melbourne, London ... continents North America, Europe, Asia, Africa ... countries Australia, France, German, China, Korea ... islands Bermuda, Hawaii ... mountains Everest, Fuji, Kilimanjaro ... states California, Victoria, Texas ...
	But we use the in names of some countries (Kingdom, Republic, States) : the United States of America (the USA), the USSR, the United Kingdom, the Philippines  ...

(ex) He visited Germany last year and He will visit the USA this year.
(ex) How long had you been in Australia?

These are examples.

	academic mathematics, politics, physics ... breakfast breakfast, lunch, dinner disease cancer, measles, mumps ... sports baseball, basketball, soccer ...
	'breakfast', 'lunch', 'dinner' are can be a countable noun or can be a uncountable noun. (first and second ex)

(ex) We had lunch at 2 PM.
(ex) I'm hungry because I had a poor breakfast.

(ex) She was teaching mathematics in high school.
(ex) He would rather play soccer than watch a soccer game.
('game' is a countable noun)

We don't use 'the' with names of company.

(ex) He worked for GM in the United States of America.
(ex) Hyundai is the biggest company in Korea.

We don't use 'the' with names of most streets, roads, squares
parks and so on.

(ex) Is there a post office near Spancer street?
(ex) Where is Seoul Park?

When we use some word which indicate social positions, we do
not use 'the'.

(ex) President Kim was elected last year.
(ex) Many people love Princess Diana.