Defining a trade deficit and a trade surplus

Question

Please answer the three questions below.

Question:

Define a trade deficit and a trade surplus. What are the implications of a long-term trade deficit or trade surplus? What techniques are available to correct balance of payment deficit or surplus?

Please provide proper references and cites properly format. If you are using a book, please provide chapter, paragraph and/or page number(s)

Also, when providing websites- internet references, please make sure I am allowed or able to retrieve those references (they should NOT be from subscribed websites etc).