The four main types of referrals are customer referrals, employee referrals, strategic partnerships, and digital referrals. Customer referrals occur when a satisfied customer shares their experience with your product or service with friends and family. Employee referrals involve current or former employees recommending candidates they know for open positions. Strategic partnerships happen when two businesses collaborate to expand each other’s reach and grow their customer base. Finally, digital referrals come in online ad campaigns that draw attention to the referral program and incentivize people to join.