JMeter provides several timer elements that can be used to simulate delays between requests in your test plan. These timers are used to introduce a delay between requests so that they can more closely simulate real-world scenarios where users take some time to interact with the application.

Here are some of the timer elements available in JMeter:

1. Constant Timer: This timer introduces a fixed delay between requests. You can set the delay time in milliseconds in the Timer element's configuration.

2. Gaussian Random Timer: This timer introduces a random delay between requests with a Gaussian distribution. You can set the delay time and the deviation in milliseconds in the Timer element's configuration.

3. Uniform Random Timer: This timer introduces a random delay between requests with a uniform distribution. You can set the delay time and the range in milliseconds in the Timer element's configuration.

4. Poisson Random Timer: This timer introduces a delay between requests based on a Poisson distribution. You can set the mean delay time in milliseconds in the Timer element's configuration.

5. BeanShell Timer: This timer allows you to write your own Java code to calculate the delay time between requests. You can write a BeanShell script that calculates the delay time and returns it as a long value.

To add a timer element to your test plan, you can right-click on a sampler or a controller and select "Add" > "Timer" from the context menu. Then, you can choose the type of timer you want to add and configure its properties.

Timers can be added to individual samplers or to a controller that groups multiple samplers. You can also use a Test Action sampler to add a delay that is not associated with a specific request.