While DNA is typically double-stranded, RNA exists as a single strand. This single-stranded structure allows RNA to perform a variety of functions in the cell, including:

* Carrying genetic information from DNA to ribosomes for protein synthesis (mRNA)

* Acting as a template for protein synthesis (tRNA)

* Regulating gene expression (microRNA)

It's important to note that RNA can sometimes fold back on itself to form short double-stranded regions, but its overall structure is single-stranded.