Short answers, pulled from the story.
A limited series is a comics series with a predetermined number of issues that differs from an ongoing series because the number of issues is finite and determined before production begins. This structure also differs from a one shot since it is composed of multiple issues rather than just a single installment.
DC Comics published World of Krypton as their first experimental limited series in 1979 during the process of recovering from the DC Implosion which had disrupted their publishing schedule. The new format allowed the company to tell stories that may not have fit into an ongoing series without the risk and obligations of an ongoing monthly title.
Camelot 3000 debuted in 1982 as the first limited series to run to 12 issues. DC coined the term maxiseries as a promotional description for this specific type of long-running work after seeing its success.
Watchmen arrived in 1986 written by Alan Moore with art by Dave Gibbons across 12 issues. The publication elevated the medium by demonstrating that short-form comics could achieve critical acclaim through higher production values and more mature storytelling approaches.