Multi-channel attribution is the process of assigning credit to conversion paths that span multiple channels. In other words, it allows you to see the bigger picture of how your marketing efforts are working together to generate leads and sales. By understanding which channels drive the most conversions, you can make more informed decisions about where to allocate your marketing budget. This helps you understand the role that each channel plays in the conversion process and makes it easier to optimize your campaigns for better results. The most common attribution models are last-click, first-click, and linear. 

Example

For example, a lead might first see a display ad, then click on a paid search ad, and finally convert to your website after seeing a retargeting ad. In this case, multi-channel attribution would be used to assign credit to all three of those marketing channels.