# Tutorial: Transactions overview

The tutorials in this section demonstrate different transaction models that Tilia services support.

Usage note
You must run all of the **[User account tutorials](/tutorials/user-accounts)** at least one time before you run the tutorials in this section.
The tutorials in this section use the environment variables that the **User account tutorials** initialize.

If a request requires data that has not yet been configured, it
displays an error message in the Postman console log.

## Choose a transaction model

The following table lists the transaction models demonstrated in these tutorials.
Note that you must have a valid [access token](#get-an-access-token) to run the exercises in a tutorial.

| Transaction model | Currency used | Users involved | Description |
|  --- | --- | --- | --- |
| [Standard user-to-user](/tutorials/transactions/tutorial_txn_standard) | TIL tokens | payerrecipient | A standard user-to-user transaction |
| [Standard user-to-user with royalties](/tutorials/transactions/tutorial_txn_royalties) | TIL tokens | payerrecipientcreator | A user-to-user transaction that pays the creator a portion of the transaction |
| [User-to-user with escrow](/tutorials/transactions/tutorial_txn_escrow) | TIL tokens | payerrecipient | A standard user-to-user transaction that holds the funds in escrow |
| [User-to-publisher and user-to-user using Checkout UI](/tutorials/transactions/tutorial_txn_checkout) | USD fiat currency | payerpublisherrecipient | A user's purchases from the publisher and another user using the Tilia-hosted checkout widget |
| [NFT purchase from publisher](/tutorials/transactions/tutorial_txn_nft) | USD fiat currency | payerpublisher | The recipient requests a payout of convertible tokens to fiat currency |
| [Payout to user](/tutorials/transactions/tutorial_txn_payout) | TIL tokentsUSD fiat currency | recipient | A purchase from the publisher using the payer's payment method and holding the funds in escrow |


In addition to the transaction examples, this tutorial presents several methods for
getting information about transactions in  [Transaction info](/tutorials/transactions/tutorial_txn_info)

## Get an access token

Get an access token for the tutorials in this section.

Each request requires an authentication header with a valid access token that has the necessary scope for the request.

This request obtains an access token with the scopes required for all the tutorials in this section.
After you've requested the access token for the collection, Postman adds the required authentication header
to the subsequent requests in the collection.

For more information about access tokens, visit .

**To get your access token for the transaction tutorials, in Postman:**

1. Near the top right of the request, above the request URL, choose the **Tilia Client Info** environment.
2. In the **Explore Tilia transactions** collection, in the **Start here** folder, open the **Get an access token** request,
and then choose the **Body** tab.
3. In the **Body** tab, notice that the `client_id` and `client_secret` properties use
the environment variables that you assigned in [Get started with the tutorials](/tutorials/tutorial_get_started).
4. Choose **Send** (to the right of the request's **URL** field) to request the access token.
5. If the request was successful:
  1. The `access_token` value is saved in the **last_tilia_access_token** collection variable.
  2. Review the response body.
  3. Review the **Collection variables** to confirm that the
**Current value** of **last_tilia_access_token** also has the token value.
6. If the request returns an error, review the response body for more information about the problem.
Also, check that the correct environment is selected and that there are no errors
in your Tilia developer credential values.


A typical response body is shown in [Get an access token (User accounts)](/tutorials/user-accounts#get-an-access-token).

With that, you're ready to try the rest of the requests in the collection.

### Your access token is only good for an hour

In the response body of the **Get an access token** request, notice the value of the `expires_in` property.
That value is the duration, in seconds, that the token is valid.
In this case, the token is valid for 3,600 seconds, which is one hour.
After using the access token for more than an hour, your requests return a response body like the following.


```json
{    
    "status": "Failure", 
    "message": [],
    "codes": [],
    "payload": { 
        "error": "token is expired"
    }
}
```

If you get this response body later, return to this collection's **Start here** folder,
open the **Get access token** request, and then send it again to get a new token for the collection.

## Next steps

Choose a Tilia transaction to explore from the preceding table, or start with the [Standard user-to-user transaction](/tutorials/transactions/tutorial_txn_standard).