The most important assistant to the director; the person who is responsible for running the show during the performance and the director during auditions and the rehearsal process by taking notes, recording blocking, and scheduling rehearsals.

The person responsible for all these things is the stage manager.

Explanation:

Stage manager is one of the jobs that most cast doubt on the roles a stage technician can perform. This is because, unlike the more art-focused theatrical direction, scene direction encompasses the whole operation of a show, from planning and organization to operation, assembly and disassembly - but always paying attention to aesthetic issues. This professional is therefore a kind of general coordinator of all backstage activities.

In other words, we can say that this professional is the director's most important assistant; The person responsible for executing the program during the presentation and assisting the director during the auditions and rehearsal process by taking notes, blocking the recording and scheduling rehearsals.