1.A letter of credit is a written undertaking (承诺，保证) issued by a bank given to the seller at the request and in accordance with the instructions of the buyer to effect payment at sight or at a determinable future time up to a stated sum of money and against stipulated (规定的) documents which are complied with(符合) the terms and condition of the credit.信用证:（LETTER OF CREDIT,简写为L/C）是银行应买方要求和指示向卖方开立的、在一定期限内凭规定的单据符合信用证条款，即期或在一个可以确定的将来日期，兑付一定金额的书面承诺。2.Remittance refers to a bank, at the request of its customer, transfer a certain sum of money to its oversea branch or correspondent bank instructing it to pay to a named person domiciled (定居的) in that country.国际汇兑：又称国外汇兑，指的是通过银行的汇兑来实现国与国之间债权债务的清偿和国际资金的转移。3.A letter of guarantee (L/G) is a written promise issued by a bank at the request of its customer, undertaking(承诺) to make payment to the beneficiary within the limits of a stated sum of money in the event of default (不履行责任) by the principal.A letter of guarantee (L/G) is a written promise by a bank at the request of its customer (the principal applicant), undertaking to payment to the beneficiary within the limits of a stated sum of money in the event of non-performance of the contractual obligations by the principal.银行保证函（banker's letter of guarantee)，简写为L/G），又称银行保证书、银行保函、或简称保函，它是指银行应委托人的申请向受益人开立的一种书面凭证，保证申请人按规定履行合同，否则由银行负责偿付债款。4.Collection means an arrangement whereby the goods are shipped and the relevant bills of exchange are drawn on the buyer, and/or documents are sent to the seller’s bank with clear instruction through one of its correspondent banks located in domicile (住所)of the buyer.托收（Collection）是出口方委托本地银行根据其要求通过进口地银行向进口方提示单据，收取货款的结算方式。
常用付款方式
前T/T ? 电汇
即拿到客户的定单后，业务员立即开形式发票（Proforma Invoice）给客户打款（一般是定金，总货款的30-50%）。客户拿到形式发票后，在他国家的银行打款。一般4个工作日能到指定帐户。生产完产品后，通知客户，开形式发票给客户打余款。
此方法可以灵活运用，但最大限度只能为：即先让客户打定金，等出货后拿到提单，将提单副本的复印件提供给客户，安排余款。但是前提条件是货带由我方指定。
后T/T?? ? ?
后TT是指厂家收到定金后，开始生产，生产完毕后交货并提供给客户单证。客户收到货后在一定期限内将余款打到厂家/供应商指定的帐户。此操作风险极大。不适合采用。
L/C(信用证)?? ? ?
信用证是银行用以保证买方或进口方有支付能力的凭证。买方先将货款交存银行，由银行开立信用证，通知异地卖方开户银行转告卖方，卖方按合同和信用证规定的条款发货，银行代买方付款。信用证是对买卖双方都比较公平的交易方式。