Definition of Series B Round
The phrase Series B Round refers to a second round of venture capital financing.
When a company raises venture capital in a preferred stock financing, the shares of preferred stock sold in a given financing round are defined with a letter. Shares sold in the first financing are "Series A" shares. Subsequent rounds are called "B", "C", "D", and so on.
Shares in a given series all have the same rights, but shares in different series may have different rights.
Receiving a Series B round is generally a positive occasion for a venture-backed company. It means professional investors are sufficiently interested in the company to provide additional funds after the Series A round of financing.