An ideal customer profile (ICP) is a description of a customer that would benefit the most from your offering while providing you significant value in exchange.
For B2B SaaS businesses, the ICP represents the type of customer companies sales teams should focus on acquiring. In this context, an ICP is different from a user persona; Think of user personas as people who work for your ICP.
Besides helping with marketing and sales efforts, there are additional advantages to defining an ICP from a CS lens. The closer customers are to ICP, the better CS teams can help them meet their goals. More importantly, it can help simplify and streamline onboarding thereby reducing customer churn and increasing CLV (Customer Lifetime Value). In the long term, having an ICP (that both sales and CS teams have developed together, ideally) can help both teams work better together towards the business goals.
Another advantage is that using ICPs to find the right customers creates more referenceable customers who are also more likely to recommend your product/service because it provides real value to them and others like them.