In modern theatre, masks continue to serve several purposes, each enhancing the performance in different ways. Here are some key uses:

1. Character Transformation: Masks can help an actor fully transform into a character, providing a visual shorthand for traits, emotions, or archetypes. They allow actors to step away from their own identity and embody the essence of the character more fully. 
2. Symbolism and Expression: Masks can represent abstract concepts or themes, such as fear, love, or death, conveying these ideas visually. They often exaggerate features or expressions to communicate emotions that might be more subtle or complex when portrayed without them.
3. Exaggeration of Features or Emotions: In the style of commedia dell’arte, for instance, masks can exaggerate certain features (like a large nose for a character who is sneaky or a stern brow for authority), making the characters instantly recognizable and their motivations clear.
4. Creating an Otherworldly or Mythical Atmosphere: Masks are frequently used to evoke the supernatural or mythical elements of a story. Characters like gods, spirits, or creatures might wear masks to separate them from human figures and to emphasize their otherness.
5. Physical and Vocal Challenge: Masks can alter an actor’s movements and speech, forcing them to find new ways to express themselves physically and vocally. This challenge can lead to more dynamic and heightened performances.
6. Removing Realism: In contrast to naturalistic theatre, masks can remove the expectation of realism and allow for more stylized, symbolic performances. This is especially common in experimental or avant-garde theatre, where the emphasis is on abstraction and interpretation rather than literal representation.
7. Cultural Tradition: Masks have a deep-rooted presence in many global theatre traditions (like Japanese Noh theatre, African performance, or ancient Greek theatre). In modern performances, masks can maintain a link to these cultural heritages, adding layers of meaning to the work.
8. Anonymity and Universality: By hiding the actor’s identity, masks can make the character more universal or anonymous, focusing attention on the ideas, themes, or actions rather than the individual performer. This can be especially powerful in ensemble pieces or when a character represents a collective identity.

Ultimately, the mask can be a tool for broadening the expressive possibilities in theatre, allowing for a deeper connection to the material and the audience.