Primarily used as a suffix in compounds like 相談 (consultation), 会談 (talks), 雑談 (chat), or 体験談 (personal account). As a standalone noun, it is literary or formal.
His personal story was very interesting.
Talks were held between the leaders of the two countries.
談 (だん, 'talk') and 壇 (だん, 'platform, dais') share the same reading but differ entirely in meaning, so they must be told apart by context or kanji.
譚 (たん) means 'tale/story' and appears as a suffix like 英雄譚, while 談 (だん) means 'talk/discussion' as in 相談; the two kanji look similar (both contain 言) but are unrelated in meaning and pronunciation.
From Middle Chinese 談 (dɑm). Used in Japanese as a bound morpheme meaning 'talk' or 'discussion', appearing in many Sino-Japanese compounds.
digression; aside; tangent
out-of-court settlement; private settlement
conversation; discussion; talk
business discussion; negotiation
moving tale; heartwarming story
friendly chat; pleasant conversation; lighthearted talk
marriage proposal; marriage talks
kōdan; dramatic storytelling
written communication; communicating by writing
chat; rambling talk; desultory conversation
failure story; horror story
pleasant chat; friendly talk
breaking off; cancellation
three-way conversation; tripartite talk; roundtable discussion
private talk; secret conversation; confidential discussion
free talk; irresponsible talk
dirty talk; lewd conversation; smut
negotiations; bargaining; talks; making demands
romantic story; colorful story; highly embellished story
bid rigging; collusion; illegal price-fixing · consultation; discussion; conference
informal discussion; chat; talk · formal talk; lecture; sermon · admonition; reprimand · Buddhist sermon; preaching · consultation; conference; discussion