Please forgive my ignorance, but what is a " bump". Ive seen the phrase used in replies many times and always thought "What on earth!"

A "bump" is something people use to bump the message to the front page so everyone can see it. :D

Each time someone posts a reply or a new topic, the other topics are pushed down. And since there can only be a certain amount of topics on a page, your post can end up on the second page, for example, where noone is likely to see it, let alone reply to it.
If your question is still unanswered when the topic is on page two, you can post a reply to get it back on top.
Traditionally, the contents of that reply are something like:
<font size=6>Bump</font>
Others will see the post (they may have missed it before), read it and hopefully provide a helpful answer.

A bump means nothing other than: read this, I want an answer.

Or: Hello, is anyone stil here?
in certain threads.

Wonderful!

thanks for clearing that up for me - I like to learn new things!

Muchos Muchos Thankos