Heading 1

Used mostly for highest level page titling, and maybe a few other use cases.

Heading 2

Used for section titling. Depending on the number of sections on a page, this could be seen several times per page.

Heading 3

Used for subsection titling, possibly including special element titles like sliders and such. 

Heading 4

Subheader that will be used fairly infrequently. 

Heading 5

Subheader that will be used fairly infrequently.