Short definition
A sales pipeline is the visual map of the stages a deal moves through from first contact to closed sale, used to forecast revenue and spot stuck deals.
In depth
A typical service-business pipeline has 4–7 stages: New Lead, Contacted, Estimate Sent, Negotiation, Won, Lost. Each stage has a probability and a dollar value attached. Pipelines surface bottlenecks (deals dying at 'Estimate Sent' suggest a pricing or follow-up problem) and enable forecasting (sum of weighted deal values per stage). Pipelines live inside CRMs and are most powerful when paired with automation that pushes deals forward without human nudging.
Example
A landscaping firm sees 60% of deals stall at 'Estimate Sent'. They add an automated 3-touch follow-up sequence and close-rate from that stage doubles.