Explain how to use ad customizers with custom parameters in Bing Ads.

Using ad customizers with custom parameters in Bing Ads allows advertisers to dynamically insert personalized information into ad text based on specific attributes defined by the advertiser. Here's how you can effectively use ad customizers with custom parameters:

### Setting Up Ad Customizers with Custom Parameters

1. **Define Custom Parameters**:
   - Start by defining the custom parameters you want to use in your ad customizers. These parameters can include attributes such as product names, prices, promotions, or any other dynamic content you wish to display.
   - Example custom parameter: `{=Product.Price:default text}`

2. **Create a Customizer Feed**:
   - Prepare a data feed (spreadsheet) that contains the custom parameters and their corresponding values. Each row in the feed represents a set of values for a specific ad customizer attribute.
   - Ensure the feed is structured correctly with columns for each attribute (parameter) and rows for different variations or data points.

3. **Upload the Feed to Bing Ads**:
   - Log in to your Bing Ads account and navigate to the Shared Library section.
   - Select "Business Data" and then "Customizers" to access the customizers management interface.
   - Upload your customizer feed (spreadsheet) containing the custom parameters and their values. Bing Ads will validate the feed and allow you to map the columns to the corresponding attributes.

4. **Implement Ad Customizers in Ad Copy**:
   - Once the feed is uploaded and validated, you can start implementing ad customizers in your ad copy. Use the following syntax to insert custom parameters into your ads:
   - Example: `{=FeedName.AttributeName:default text}`

5. **Test and Preview**:
   - Use Bing Ads' ad preview tool to test how your ads appear with ad customizers. Verify that the custom parameters are displaying correctly and dynamically updating based on the data feed.
   - Make adjustments as needed to ensure accuracy and relevance of the information displayed in your ads.

### Example Scenario:

Suppose you're running a campaign for an e-commerce website selling various products, and you want to dynamically insert product names and prices into your ads using ad customizers with custom parameters.

- **Customizer Feed Example** (CSV format):
 
  ```
  Product, Price
  Laptop, $999
  Smartphone, $699
  Tablet, $449
  ```

- **Ad Copy Example**:

  ```
  Save on {=Product:default text} - Only {=Price:default text}!
  ```

In this example:
- `{=Product:default text}` dynamically inserts the product name from the feed (e.g., Laptop, Smartphone, Tablet).
- `{=Price:default text}` dynamically inserts the price associated with each product (e.g., $999, $699, $449).

### Best Practices for Using Ad Customizers with Custom Parameters

- **Maintain Feed Accuracy**: Ensure that your customizer feed is regularly updated to reflect accurate product information, prices, promotions, etc.
- **Monitor Performance**: Track key metrics such as CTR, conversion rate, and ROAS to evaluate the effectiveness of ad customizers with custom parameters.
- **Compliance**: Adhere to Bing Ads' policies and guidelines to ensure that ad content using customizers is accurate, transparent, and compliant with advertising standards.

By effectively using ad customizers with custom parameters in Bing Ads, advertisers can create more relevant and engaging ad experiences that resonate with their target audience, ultimately driving higher engagement and conversion rates.