What are lymph nodes and their function?!
Question:
What are lymph nodes and their function?
Answers:
The first two answers are correct, but incomplete. The lymph system is a second circulatory system throughout your body. When fluid leaks out of your bloodstream (and there are lots of reasons for it to do so), the lymph system recovers that fluid and returns it to the blood stream. Nodes themselves gather foreign material and pathogens and hold them for destruction by WBC's; I seem to recall that lymph nodes play a more active role as well but can not remember it.
A swollen lymph node is still pretty small, it feels hard and slightly mobile under the skin.
You should look at the diagram of lymph nodes and lymphatic vessels, there are some peculiarities in the structure.