Why are there grooves on a quarter?

The grooves are called "reeding" and are a holdover from the days when coins were made of silver. Before reeding was introduced, criminals would scrape the edges of silver coins, removing a small amount of metal from each one until they accumulated enough to sell, a practice called shaving. Edges were reeded to make it easier to detect when a coin had been shaved.

Today many countries, but not the US, use distinctive patterns of reeding on the edges of their coins to make them distinguishable by touch which helps people with visual impairments.