What is the meaning of H-system?

A convention whereby Esperanto’s circumflex accents (ĉ, ĝ, ĥ, ĵ, ŝ) are replaced by an h after the letter (ch, gh, hh, jh, sh) and the breve (ŭ) is left out entirely (u), for convenience of typing.

Source: wiktionary.org