Do not confuse
Project ticketing and ITSM are not synonyms.
A ticket is a record: someone asks for something, or reports that something does not work, and the request becomes traceable. Project ticketing software knows how to receive these requests, sort them, assign them, chase them and close them. Atlassian, which publishes Jira and Jira Service Management, puts it in one sentence: IT ticketing systems are only one aspect of ITSM.
ITSM, IT service management, is of another order. IBM defines it as the practice of planning, implementing, managing and optimizing the end-to-end delivery of IT services, to meet users' needs and the organization's objectives, and points out that ITIL is its most widespread reference framework. An ITSM therefore organizes processes: restoring a service after an incident, treating the cause of repeated incidents, getting a change through without breaking production, keeping a catalog and measuring service levels.
There are thus two distinct practices, serving different needs. Project ticketing tracks the requests and problems of a project or a product: a defect found in acceptance testing, a requested enhancement, a technical task. Incident ticketing, within an ITSM, serves operational upkeep, support and operations. On this site, "project ticketing" means the first, and we write "ITSM" for the second.