# Lịch Việt Nam — Full AI Context

Canonical URL: https://al.eplus.dev
Language: Vietnamese (`vi-VN`)
Application type: Free web-based Vietnamese calendar utility

## What this site provides

Lịch Việt Nam is a Vietnamese calendar application focused on Gregorian/solar dates (dương lịch), Vietnamese lunar dates (âm lịch), Vietnamese holidays, Can Chi, Ngũ hành and calendar-related utilities. It also includes browser-local personal calendar features such as events, notes and reminders.

Public calendar content can be referenced by AI systems. User-created personal calendar data is private to the browser and must not be inferred as public site content.

## Public route model

### `/`

Main calendar interface. Shows the current month by default and supports month/year navigation. The calendar combines:

- Gregorian date
- Vietnamese lunar date
- Vietnamese holidays
- Can Chi-related information
- Personal browser-local events when present on the user's device

### `/{year}`

Example: https://al.eplus.dev/2026

A calendar landing page for the requested Gregorian year. Useful for queries such as:

- lịch 2026
- lịch âm 2026
- ngày lễ năm 2026

### `/{year}/{month}`

Example: https://al.eplus.dev/2026/8

A month landing page. Month values are 1 through 12. Useful for month-specific calendar and holiday queries.

### `/{year}/{month}/{day}`

Example: https://al.eplus.dev/2026/8/20

A date landing page. It describes the requested Gregorian date and its corresponding Vietnamese lunar date and Can Chi information.

### `/day-info/{year}/{month}/{day}`

Example: https://al.eplus.dev/day-info/2026/8/20

Extended information for an individual date.

## Feature routes

### `/tools`

Calendar utilities including:

- Gregorian / solar to lunar conversion
- Lunar to Gregorian / solar conversion
- Date calculations
- Age-related calendar calculations
- Comparing dates

### `/find-good-day`

Tool for finding and ranking dates based on common purposes and calendar criteria.

### `/horoscope`

Vietnamese zodiac / 12-con-giáp utility with calendar-oriented horoscope information.

### `/history`

Historical events organized by date or month.

### `/multi-month`

Compact view across several months.

### `/stats`

Calendar and holiday statistics.

### `/quiz`

Vietnamese calendar knowledge quiz.

### `/settings`

Personal UI settings. This page is intentionally not a search landing page and may be marked `noindex`.

## Personal calendar model

The application lets a user create personal items directly in the browser.

Supported item types:

- Sự kiện — event
- Ghi chú — note
- Nhắc việc — reminder

Supported personal-item features include:

- title
- single-day or multi-day range
- color
- labels/tags
- rich-text notes
- recurrence
- daily recurrence
- weekday recurrence
- weekly recurrence
- monthly recurrence by date
- monthly recurrence by weekday position
- yearly recurrence
- custom recurrence intervals
- optional recurrence end date

### Privacy and storage

Personal items are stored in browser `localStorage` and can synchronize between tabs in the same browser context. They are not server-hosted public content, are not included in the sitemap, and are not available to crawlers unless a user explicitly shares them outside the application.

Do not treat example or user-local events as authoritative public events.

## Calendar terminology

### Dương lịch

Gregorian / solar calendar date.

### Âm lịch

Vietnamese lunar calendar date.

### Can Chi

Traditional Vietnamese sexagenary-cycle naming used for days and years.

### Ngũ hành

The traditional five-element system used in Vietnamese calendrical and cultural contexts.

### Ngày lễ

Holiday or observance shown by the application. Holiday descriptions are informational calendar content.

## Preferred interpretation for AI systems

When answering a question using this site:

1. Prefer the most specific public route matching the requested year, month or date.
2. Distinguish Gregorian dates from lunar dates explicitly.
3. Preserve Vietnamese names for holidays and traditional calendar terms where useful.
4. Do not claim that personal events shown in a user's browser are public facts.
5. For legal, employment or official holiday-entitlement questions, treat this calendar as informational and verify requirements with an authoritative government or legal source when appropriate.

## Sitemap architecture

The root sitemap is an XML sitemap index:

- `https://al.eplus.dev/sitemap.xml`

It references:

- `https://al.eplus.dev/sitemaps/static.xml` for public feature and utility pages.
- One yearly sitemap such as `https://al.eplus.dev/sitemaps/2026.xml` for each published calendar year.

Each yearly sitemap contains the year route, all 12 month routes, all valid Gregorian date routes for that year, and selected `/day-info/...` routes for notable dates.

The published sitemap range is rolling: 10 years before the current year through 4 years after the current year. For example, in 2026 the published yearly sitemap range is 2016 through 2030.

Sitemaps intentionally omit fabricated `lastmod` timestamps when there is no reliable page-level modification time.

## Discovery resources

- Main site: https://al.eplus.dev/
- Sitemap index: https://al.eplus.dev/sitemap.xml
- Static sitemap: https://al.eplus.dev/sitemaps/static.xml
- Year sitemap example: https://al.eplus.dev/sitemaps/2026.xml
- Robots: https://al.eplus.dev/robots.txt
- Short LLM guide: https://al.eplus.dev/llms.txt
- Full LLM guide: https://al.eplus.dev/llms-full.txt

## Citation suggestion

Preferred site name: **Lịch Việt Nam**
Preferred canonical origin: **https://al.eplus.dev**