Naming a child is seen as an immensely significant responsibility, as it will determine the meaning, encompassing the future and destiny of that child.
Naming a child is regarded as an immensely significant responsibility, as it will decide the meaning, harboring the future, and destiny of that child. Therefore, since ancient times, when naming children, Vietnamese people often don't forget the prefix: 'Van' for boys, and 'Thi' for girls to distinguish gender in daily addresses.
Since ancient times, Vietnamese naming conventions have featured phrases frequently prefixed before the main name such as 'nam Van nu Thi,' which is also a longstanding tradition upheld to this day.
This is akin to the Western practice where one can discern whether an individual is male or female by its inherent characteristics. Ancient Vietnamese did the same, with elders often prefixing 'Van' for boys and 'Thi' for girls to aid in gender differentiation in everyday address.
So why was it done this way?

Boys' names often prefixed with 'Van'
In Vietnamese men's names, there are many words used as middle names, but 'Thị' is never used. The most common is still 'Van'.
Our ancestors have long passed down the saying 'one man equals ten women', indicating that a son is worth ten daughters, as historically, only men were valued members of society.
They were sent to school, took exams to gain knowledge, and would later contribute greatly to the nation, known as those with 'scholarly virtues'.

Ultimately, the habit of naming sons gradually formed and deeply ingrained in the subconscious of many generations of Vietnamese people until now.
Therefore, nowadays, many people often name their sons following the formula: Surname + Van + Given Name.
Even as society develops, some parents still retain 'Van' in their children's names as a means to honor their ancestral heritage, while also hoping that their offspring will have a prosperous future, with a smooth career path ahead.
Girls' names often prefixed with 'Thị'
The origin of the term 'Thị' in girls' middle names began to appear after the first Northern domination period. 'Thị' is a Sino-Vietnamese word used to refer to women.
In the book 'Từ nguyên từ điển', there's a phrase 'Phu nhân xưng thị' (women call themselves 'thị'). Additionally, it's a term that women use to refer to themselves.
There has been much controversy surrounding the use of 'Thị' to name daughters. The original meaning of 'Thị' is surname or family name. In Chinese culture, 'Thị' is often used after the husband's name instead of the wife's given name.
However, in Vietnam, there's a difference: Women in the esteemed households of Vietnam still retain their paternal surname and add 'Thị' afterward.

For example: before ascending to the queen's throne, Cù Hậu was referred to as Cù Thị, and occasionally in ancient documents, titles like Queen Dương Thị, Lady Nguyễn Thị... can still be found, translated as Mrs. Dương's queen, Lady Nguyễn's consort...
By the 15th century, the term 'Thị' became closely associated with the names and surnames of females, affirming their roots, forming the naming convention: Surname + Thị + Given Name.
However, nowadays, the naming convention 'nam Van nu Thị' seems to have changed somewhat. Due to international integration and cultural development, things have gradually changed. Many families have used alternative middle names with more beautiful meanings to combine with their formal names.
Nevertheless, the practice of naming 'nam Van nu Thị' still persists as a deeply ingrained habit and cultural tradition among the Vietnamese people up to now.