What is Single Sign-On for business apps?

Short answer

Single Sign-On (SSO) means you authenticate once and then open every connected application without entering a password again.
In 4b2b.net one active account opens invoicing, CRM, HR, contracts, projects and hosting from the same session.
SSO removes the pile of separate passwords, lowers the security risk and shortens onboarding for a new hire.
Access stays granular through roles: an accountant sees invoicing and accounting, not the CRM or HR.

Without SSO, an employee ends up managing 8 to 15 passwords for business applications.
Password resets consume administration time that a small company pays for directly.
Data-protection rules expect access controls you can demonstrate, and central SSO makes audits and revocation simple.
4b2b.net implements SSO with JWT — an industry standard, so external systems can use the same tokens.

In United States, who touched the records behind an IRS filing should be answerable from the system itself.
Documents sent through voluntary e-invoicing exchange over the DBNAlliance network and state sales-tax filing are issued by an identifiable account, not by an anonymous user.
The people entitled to represent the company, as recorded with the Secretary of State, are the ones who should be able to sign in the panel.
Data-protection rules require access to end when employment ends; with SSO that is one action in one place.

Example: a manager opens the panel, reviews invoicing, approves a CRM quote and signs a contract — without authenticating again.
Example: when an employee leaves, the administrator disables the account once and access to every module is revoked immediately.

Confusing SSO with one shared password — SSO means one authenticated session, not the same password everywhere.
Treating SSO as enough security on its own — the single account still needs a strong password and tight per-module roles.
Giving every employee full access instead of setting permissions per role.