#software-engineering #documentation
## What is D2?
**D2** is a diagram scripting language that turns text to diagrams. It stands for **Declarative Diagramming**. Declarative, as in, you describe what you want diagrammed, it generates the image.
For example, download the CLI, create a file named `input.d2`, copy paste the following, run this command, and you get the image below.
```
1d2 --theme=300 --dark-theme=200 -l elk --pad 0 ./input.d2
```
```d2
network: {
cell tower: {
satellites: {
shape: stored_data
style.multiple: true
}
transmitter
satellites -> transmitter: send
satellites -> transmitter: send
satellites -> transmitter: send
}
online portal: {
ui: {shape: hexagon}
}
data processor: {
storage: {
shape: cylinder
style.multiple: true
}
}
cell tower.transmitter -> data processor.storage: phone logs
}
user: {
shape: person
width: 130
}
user -> network.cell tower: make call
user -> network.online portal.ui: access {
style.stroke-dash: 3
}
api server -> network.online portal.ui: display
api server -> logs: persist
logs: {shape: page; style.multiple: true}
network.data processor -> api server
```
## Using the CLI watch mode[](https://d2lang.com/tour/intro#using-the-cli-watch-mode "Direct link to Using the CLI watch mode")
You can finish this tour in about 5-10 minutes, and at the end, there's a cheat sheet you can download and refer to. If you want just the bare essentials, [Getting Started](https://d2lang.com/tour/hello-world) takes ~2 mins.
## Any alternatives and comparison?
[Frequently asked questions (FAQ) | D2 Documentation (d2lang.com)](https://d2lang.com/tour/faq/#how-does-this-compare-to-mermaid-graphviz-plantuml)