Short answers, pulled from the story.
The Sanskrit word sutra means string or thread. Its root is siv that which sews and holds things together. This image of a thread weaving disparate elements into a single fabric defines the genre across Hinduism Buddhism and Jainism.
Sutras first appear in the Brahmana and Aranyaka layers of Vedic literature from the late second millennium BCE. These oldest manuscripts survive from the period between 600 BCE and 200 BCE known as the sutras period. The Aitareya Aranyaka serves as a primary collection of sutras within these ancient texts.
Badarayna composed this text likely between 200 BCE and 200 CE. The Brahma Sutras contain 555 sutras across four chapters summarizing philosophical ideas from Upanishads. These texts form foundational pillars for distinct schools of Hindu philosophy including Vedanta Samkhya and Nyaya traditions.
Buddhist suttas differ significantly from Hindu sutras by being quite lengthy rather than aphoristic. The term likely derives from Sanskrit sukta meaning well spoken reflecting belief that all words spoken by Buddha were well-spoken. These teachings constitute the second basket or pitaka of Pali Canon known as Sutta Pitaka.
Tattvartha Sutra stands as most authoritative philosophical text accepted by all four Jainism sects summarizing foundations of Jainism completely. Jain sutras functioned as fixed texts meant to be memorized by monastic communities. Acaranga Sutra exists in sutra format within Agamas alongside biographies of Jain Tirthankaras discussing aspects of ascetic and lay life.