The Vietnamese tourist visa is categorized as a C1 visa. The maximum validity is 30 days (for both single or multiple entries).
 

All foreigners (1) who are entering Vietnam for the purposes of tourism are required to have valid passports with at least 6 months of validity remaining and Visas.There are two ways  to do this:
 

1. Apply for Vietnamese Business Visa at your nearest Vietnamese Embassy/Consulate. What you need to do is to bring your original passport, 2 passport-regulation photos and the stamping fee to the embassy or consulate (the fee varies from embassy to embassy). This method takes an average of 5 working days.
 

2. Apply for your Vietnamese visa online. For those who enter Vietnam by air, visa on arrival is a convenient and quick option. It takes only 2-3 business days to process your visa and you will receive your approval letter by email. You can  begin your visa application here
 

Notes: Visa on arrival is good for air travel only, if you wish to enter Vietnam by land or sea - you are required to obtain your visa beforehand.
 

Visa exemption:
 

Only citizens of certain countries can visit Vietnam without a visa, they are:

Nationals of most ASEAN countries: No visa is required if they plan to stay less than 30 days
Nationals of South Korea, Japan, Russia, Norway, Sweden, Denmark, and Finland: No visa is required if they plan to stay less than 15 days