Reader showing more feeds than xml page?

Can someone explain ( please )

[financialhost]

I am using standalone RSS reader & have subscribed to [rss.news.yahoo.com...] but my feeder shows 183 items while the actual xml page shows only around 20 items.

How is this possible?

Please help, i am a newbee to XML, RSS & need to understand these situations.

[werty]

Depending on your reader, it may be caching all items that are un-read by you, either that or your reader is storing all items since you subscribed to the feed.