Senbei are often eaten with green tea as a casual snack and offered to visiting house guests as a courtesy refreshment.
Senbei have several variations, including nori-wrapped, arare, Olive no Hana, soy nut, and wet.
Sweet senbei (甘味煎餅) came to Japan during the Tang dynasty, with the first recorded usage in 737 AD, and still are very similar to Tang traditional styles, originally often baked in the Kansai area, of which include the traditional "roof tile" senbei.
These include ingredients like potato and wheat flour or glutinous rice, and are similar to castella cakes, distinctly different from what most people would consider as senbei today, though traditional senbei such as this can still be found, e.g. Iga meibutsu katayaki, in Iga City.
Modern senbei versions are very inventive and may include flavorings which can range from kimchi to wasabi to curry to chocolate.