# Timers - Ruby SDK

This page describes how to set a Durable Timer using the Temporal Ruby SDK.

A [Durable Timer](/workflow-execution/timers-delays) is used to pause the execution of a Workflow for a specified
duration. A Workflow can sleep for days or even months. Timers are persisted, so even if your Worker or Temporal Service
is down when the time period completes, as soon as your Worker and Temporal Service are back up, the Durable Timer call
will resolve and your code will continue executing.

Sleeping is a resource-light operation: it does not tie up the process, and you can run millions of Timers off a single
Worker.

To add a Timer in a Workflow, use `Temporalio::Workflow.sleep`. _Technically_ `Kernel#sleep` works, but the workflow
form allows one to set a summary to view in the UI.

```ruby
# Sleep for 72 hours
Temporalio::Workflow.sleep(72 * 60 * 60, summary: 'my timer')
```

There is also a `Temporalio::Workflow.timeout` method that accepts a block and works like standard Ruby
`Timeout.timeout` if needing the ability to timeout a set of code.