邀请信分为两种：一种属于个人信函，例如邀请某人共进晚餐、参加宴会、观看电影、出席典礼等。另一种邀请信则属于事务信函，一般是邀请参加会议、学术活动等等。
一、普通邀请信
第一种邀请信邀请的对象一般是朋友、熟人，所以内容格式上的要求都比较松，可以写得随便一些。只要表明邀请的意图，说明活动的内容、时间、地点等等。但既然是邀请信，那么就一定要在信中表达非常希望对方能够参加或者出席的愿望。这种邀请信的篇幅可以非常短，下面以一封邀请看电影的短信为例：
Dear Jane,
We have four tickets for a famous film shown at Guangming Cinema, The Longest Day, Friday, the ninth. Will you join us? We'll be looking for you at eight sharp Friday night in front of the cinema, so don't disappoint us!
Warmest regards.
Alice
二、正式邀请信
第二种邀请信一般由会议或学术活动的组委会的某一个负责人来写，以组委会的名义发出，而且被邀请者通常也是属于比较有威望的人士。因此，这类邀请信的措辞要相对正式一些，语气要热情有礼。
这一类邀请信通常要包括以下内容：首先表明邀请对方参加的意图以及会议或学术活动的名称、时间、地点；然后要对被邀请者的威望和学术水平等表示推崇和赞赏，表明如果被邀请者能够接受邀请，会给会议或者活动带来很好的影响；接着要说明会议或活动的相关事宜，最好是能引起对方兴趣的事宜；当然不能忘了表达希望对方能够参加的诚意；最后还要请收信人对发出的邀请做出反馈，如确认接受邀请。下面是一封邀请对方参加学术会议的信函：
Dear Professor Wang,
On behalf of the Ohio State University and the IEEE Computer Society, I would be very pleased to invite you to attend and chair a session of the forthcoming 2004 International Conference on Parallel Data Processing to be held in Bellaire, Michigan, from October 25 to October 28, 2004.
You are an internationally acclaimed scholar and educator. Your participation will be among the highlights of the Conference.
We sincerely hope that you could accept our invitation. As you know, this is the 10th anniversary of the Conference and we plan to make it a truly international meeting. We have accepted many papers from several foreign countries, including two from China.
If you can come, please let us know as soon as possible, since we have to prepare the final program soon. We are looking forward to your acceptance.
Sincerely yours,
Peter White
三、邀请信的回复
无论是收到哪种邀请信都要复信，明确表示接受与否。而且无论接受与否都要对邀请者表示感谢。接受邀请的回信一般包含以下内容：首先感谢对方的邀请，并重述邀请信中的主要内容；然后愉快地表示接受邀请，并简要说明自己的打算；最后表示期待赴会和与对方见面的心情。下面是一封接受邀请的信，与上面第一封邀请信相对应：
Dear Alice,
Thank you very much for your invitation. It will be great pleasure for me to join you on Friday for the wonderful film. I will arrive at the cinema before eight. I look forward to meeting you on Friday.
Thank you for thinking of me.
Yours,
Jane
谢绝邀请的回信一般包含以下几方面的内容：首先还是要对对方的邀请表示感谢；然后具体说明自己无法接受邀请的原因，并对无法出席表示遗憾；最后表达自己的祝愿，即祝愿自己未能参加的会议或者活动能够顺利进行。下面是一封谢绝邀请的信，与上面的第二封邀请信相对应：
Dear Professor White,
Many thanks for your letter dated 15th August, inviting me to attend and chair a session of the forthcoming 2004 International Conference on Parallel Data Processing to be held in Bellaire, Michigan, from October 25 to 28, 2004.
Much to my regret, I shall not be able to honor the invitation because I have been suffering from a disease since this summer. I am firmly advised that it would be unwise to undertake any distant and long travel in the near future.
I feel very sad to miss the opportunity of meeting you and many others in the field of Computer Science. I wish the conference a complete success.
Faithfully yours,
Wang Xuan
