HELP beside, y do gardeners use mounds? Why do gardeners use mounds when they plant plants or seedlings??...

Why do gardeners use mounds when they plant plants or seedlings?? i hope it make sense?! and what happends when it rains close to does the plant suck the water out of the soil...? i have need of help and for a moment explenation wuld b gud!
Answers:    Only some plants to improve drainage others approaching potato are earthed up as they grow to increase tuber growth.