If we want to give a comment on a table :
COMMENT ON TABLE
If we want to give a comment on a column : COMMENT ON TABLE
The entries of these comments on the table goes in the following tables:
select * from all_tab_comments where table_name ='table_name'
select * from user_tab_comments where table_name = 'table_name'
select * from all_col_commentswhere table_name = 'table_name'
select * from user_col_commentswhere table_name = 'table_name'