Introduction:
A poster is a visual representation of information, designed to capture the attention of viewers and convey a message effectively. It typically contains a combination of text and images to communicate its main features. In this question, we are asked to identify the main feature that is NOT typically found in a poster.

Detailed Descriptions of the Theme:
Detailed descriptions of the theme are not a main feature of a poster. Posters are meant to convey information quickly and efficiently, using concise and impactful messages. They are designed to capture the viewer's attention and communicate the main message in a visually appealing and concise manner. Detailed descriptions of the theme may overwhelm the viewer and make the poster look cluttered and unattractive.

Visually Attractive/Eye-catching Layout:
One of the main features of a poster is a visually attractive and eye-catching layout. This involves using colors, fonts, and images that grab the viewer's attention and make the poster visually appealing. A well-designed layout can help convey the message effectively and make the poster stand out from others.

Phrases, Slogans, Persuasive Language in Expression:
Another main feature of a poster is the use of phrases, slogans, and persuasive language to express the message. These elements are used to capture the viewer's attention, create interest in the message, and persuade them to take action. By using persuasive language and catchy phrases, posters can effectively communicate their intended message.

Sketch or Simple Drawings:
Sketches or simple drawings are also a main feature of a poster. These visual elements help convey the message in a more engaging and memorable way. They can be used to illustrate concepts, depict scenarios, or represent ideas visually. Sketches and drawings can make the poster more visually appealing and help the viewer understand the message more easily.

Conclusion:
In conclusion, the main feature that is NOT typically found in a poster is detailed descriptions of the theme. Posters are meant to convey information quickly and effectively, using visually attractive layouts, phrases, slogans, persuasive language, and sketches or simple drawings. Detailed descriptions may clutter the poster and make it less visually appealing.