"JLPT" stands for Japanese Language Proficiency Test. Until this year, there have been four levels, with JLPT4 being the easiest level, and JLPT1 the hardest. Starting next year, there will be five levels instead, the new level being inserted right in the middle, between the levels which have been called JLPT3 and JLPT2 until now.
Some Japanese companies require having passed a certain level of the test as a requirement for employment; perhaps others adjust levels of pay depending on what levels of the test you have passed. Also, Japanese colleges and universities use this test as one way to determine whether a foreign student is prepared to attend classes taught in Japanese.
Thanks for the great sites!
I also have one with kanji www.asahi-net.or.jp/~ik2r-myr/kanji/kanji1a.htm
and one with grammar[George Washington University] www.gwu.edu/~eall/vjg/vjghomepage/vjghome.htm