在日常生活中我们通常会用口头或者电话方式邀请别人做客，但是如果遇到比较正式的场合，例如商业聚会、正式晚餐或婚礼等场合，就需要我们发送正式的书面邀请函了。
无论您要举行什么样的正式聚会，在书写邀请函时应注意包含以下几点：
Names of party hosts or sponsoring organization. 聚会主人或主办单位
Type of event (birthday party, business networking meeting, etc.). 聚会活动
Place. 地点
Date. 日期
Time. 时间
RSVP date and phone number. 回复日期及联系电话
Any special dress requirements from black-tie to bathing suits. 聚会着装要求
在书写正式邀请函时应该注意以下几点：
1. Express that you are looking forward to seeing the person. 表达你殷切的邀请之情。
2. Do not use abbreviations and do not use contractions (don't; we'll) except for name titles, such as Mr., Mrs., etc. 在信件中不要使用缩写和简写（名字前称呼除外）。
3. If dinner will be served, state two separate times: the time people can start arriving and the time dinner will be served. 如果您的聚会中包括正餐，请把正餐的时间另外标明，以便客人能够在正餐前赶到。
4. If guests are not from your local area, include a map to the location of the event. 如果客人不熟悉赴宴的路线，最好附上地图或是简单的路线指示。
5. If you are inviting someone to speak at a conference, your invitation should include the following information: 如果是正式会议等的邀请，您可能会邀请某些客人在会议上演讲或致词，那么就要在邀请函中再包括以下要点：
- Type of audience; 听众对象
- The type of speech, topic, and how long the speech should be 演讲类型及时间长短
- Any accommodations that will be made, including lodging, meals, and transportation; 为演讲客人安排的住房、三餐以及交通设备
- The name of the contact person along with phone numbers and addresses where the person can be contacted 相关联系工作人员的电话等。
一般说来，书写邀请函的注意事项就是这些。邀请函分为三种：正式的，商务的和私人的。