Most everybody requires a Passport, with a validity exceeding 6 months after the date of entry, to enter Vietnam.
Day trippers from the bordering countries of Cambodia, China and Laos bearing Identity Cards may enter Vietnam for particular purposes such as cultivation or commerce.
Foreigners usually necessitate a valid visa to enter Vietnam; citizens of member countries of ASEAN that have agreements with Vietnam do not require a visa for entry for a period not exceeding 30 days.
Vietnam visa conditions generally mirror those imposed upon Vietnamese Nationals of the Travelers home country (tit-for-tat).
Citizens of Cambodia, China, Malaysia and Laos do not require having such visas.
Visas are required by all except:

(a) Nationals of Bulgaria, Cuba, Korea (Dem Rep) and Romania;
(b) Nationals of Malaysia and Thailand for 30 days;
(c) Nationals of the Philippines for 21 days;
(d) Transit passengers continuing their journey within 72 hours, provided holding valid revisit or onward tickets. At present visas can be issued for either groups or individuals.

For security, it is advisable to carry photocopies of documents rather than originals when traveling in Vietnam.

Visa Classes

Types of visa: Tourist: (single-entry), (express service), (multiple-entry). Single-entry Business: (1 month). Multiple-entry Business: (1 month); (3 months); (6 months or more).

Tourist visas are valid for 1 month from proposed date of entry. Visas can usually be extended for another month, at extra cost, in the larger towns.
Application requirements: (1) Completed application forms (Click). (2) One passport-size photo (see note). (3) Valid passport (see note). (4) Fee (non-refundable), payable by cash or check. (5) A stamped/prepaid self-addressed envelope or courier label.
Business requirements: (1)-(4), and (5) an approval obtained through a Vietnamese sponsor.
Note: Photocopies of passports are acceptable but require two passport sized photographs with application. The visa will be issued on a form.
Do NOT ask for ‘the cheapest visa’ - specify the number of days otherwise you will be given a 15-day visa that cannot be extended.
There are also residential visas for Foreigners married to Vietnamese nationals or working in Vietnam as well as Diplomatic and other special visas.

When applying for a visa ONLY submit:

- Passport

- Application form (completed);

- ONE photograph;

- Visa fee;

- Prepaid return envelope (courier or Post Office).

The motive you should send only ONE photograph is that the Vietnamese Embassy consular officials will attach your visa in to your Passport - making it impossible to remove.