# 1. What is Step Functions

![](/files/-MCkzos-tTC-fGmYbkLi)

![](/files/-MCkzua0hmbIwLGYnPLi)

![](/files/-MCkzyp5iGtmbPWGz1ia)

![](/files/-MCl-5l1UBgvATzCxu7j)

![](/files/-MCl-FrOaQI9fmO1IOLk)

![](/files/-MCl-PPVMqT68fg1PG2E)

![](/files/-MCl-Tq5vXr3H58oLfT5)

We can also trigger execution of state machine via API GateWay as shown below:

& we can also trigger execution of state machine using Cloudwatch events as well :

![](/files/-MCl-lRN3bLG2s_Vxg64)

![](/files/-MCl-xQ6k5dyxDYoIJxa)

![](/files/-MCl06soH1Up7sTDxxUB)

Step Functions stores upto 25,000 states of machine :

![](/files/-MCl0LQUlbCoTohP_Mx-)

![](/files/-MCl0TSqsdi8d6Ey1Jdm)

Everytime the execution moves on from one state to another state is called the State transitions:

![](/files/-MCl0oDA7mH_0cRNjnld)

Costing :  AWS step functions charges for 0.2$ per transition state.

![](/files/-MCl0zXs0Op4MLqlC_WI)

![](/files/-MCl1C-7rqOfX9rdEBco)

It is the most expensive service in AWS : 

![](/files/-MCl1H6Aq1fuTg64HrZq)

![](/files/-MCl1Msq831kRkvkXmvn)


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://architectures.gitbook.io/project/aws-step-functions/step-functions-101/1.-what-is-step-functions.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.