The is Illustrator’s most iconic feature. It allows users to create precise Bézier curves and straight lines by placing anchor points and adjusting direction handles. This tool is fundamental for tracing images, creating custom typefaces, and designing crisp vector artwork. Wikipedia notes that mastery of the Pen Tool is often considered the rite of passage for professional illustrators.
The proprietary file format for Illustrator is . This format preserves layers, editability, and Illustrator-specific data. illustrator wikipedia