heard / herd are similar-sounding terms with different meanings (referred to as homophones). To better understand the differences, see below for definitions, pronunciation guides, and example sentences using each term. 👇
heard: (verb) perceive (sound) via the auditory sense. (verb) examine or hear (evidence or a case) by judicial process. (verb) receive a communication from someone. (adjective) detected or perceived by the sense of hearing.
herd: (noun) a group of cattle or sheep or other domestic mammals all of the same kind that are herded by humans. (noun) a group of wild mammals of one species that remain together: antelope or elephants or seals or whales or zebra. (verb) cause to herd, drive, or crowd together. (verb) move together, like a herd. (verb) keep, move, or drive animals.
heard: hh·ER·d
herd: hh·ER·d
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)