One essential feature of drama is conflict. Conflict is a struggle between opposing forces or characters, and it creates tension and drama in the plot. It can be external, such as a physical battle, or internal, such as a character's internal struggle with a decision.
Conflict drives the action of the play and keeps the audience engaged. It can create suspense and make the audience emotionally invested in the outcome. Without conflict, a play would be boring and lack tension.
Soliloquy, irony, and aside are other features of drama, but they are not as essential as conflict. Soliloquy is a character speaking aloud to themselves, revealing their thoughts and feelings to the audience. Irony is a situation where the opposite of what is expected happens. An aside is a character speaking directly to the audience or to another character but not meant to be heard by the other characters on stage.
While these features can add depth and complexity to a play, they are not necessary for it to be considered a drama. Conflict, on the other hand, is a crucial component of any dramatic work.