Haplogroup N is defined by a SNP-mutation from G to A called M231 at the Y-chromosome that appeared in a man that was the common ancestor of all haplogroup N people of today. This founding father may have lived as long as 20 000 to 30 000 years ago. This common father may have lived in todays South-East-Asia. The Y-DNA haplogroup N has a wide distribution primarily in Northern-Eurasia often associated (but not necessarily) with current and earlier Uralic speakers in Europe. All Y-chromosome haplogroup N holders from all the world, predicted or SNP tested welcome.

The first myth about haplogroup N I want to burst right away, most of it in Europe did not come in recorded history from the Huns and the Mongols. I quote Rootsi at University of Tartu, Estonia who is leading the research on hg N. The age of hg N3 in the Finnic-Ugric speaking population in eastern Europe suggest a much earlier arrival from the east. "From the archaeological point of view, hg N3 is spread in Europe i the area of comb-ceramic culture. It is not, however, obvious that the spread of the two can be temporarily connected, because STR diversity-based calculations of the time depth of hg N3 among the Finn-speaking European population suggests expansion time before-around the end of Pleistocene - that is long before the rise of the comb-ceramic culture in the 4th millennium BC" Source: Rootsi 2004

Y-chromosomal DNA is passed from father to son only and follow a straight direct paternal line. This means that the Y-DNA you have carry only apply for 1 of your 512 forefathers in your 10th generation back, this fraction will be even smaller as you go further back. The remaining 511 forefathers could probably belong to other haplogroups and/or having their own haplotypes, however depending on what population you belong to it should be possible to infer roughly which haplogroups your total numbers of forefathers carried. If most of your genealogy are from Britain haplogroup N would only count for a extremely small fraction of your ancestors. If you are a Finn, haplogroup N would count for over half of your male forefathers, eventually depending on what population you belong to, your total haplogroup frequency would look similar to the weighted average of the populations your ancestor belonged to.

What haplogroup or subclade of the haplogroup you belong to can be determined in two different ways 1) by Y-SNP and 2) by prediction using Y-STR markers. Using Y-SNP categorise your haplogroup with certainty and using Y-STR categorise your haplogroup reasonably accurately with statistics because Y-STR haplotypes correlate with Y-SNP in most cases. FTDNA uses by default prediction but do offer deep subclade and LLY22G/M231 backbone SNP test. The Y-SNP mutate rarely on the same spot. We are talking mostly about thousands of years. The Y-STR on the other hand mutate more rapidly and have more markers and are more useful to determine closer relationship within the last thousand years. Optimal combination are using both Y-SNP and Y-STR test because it is then possible to exclude similarity by state in the Y-STR, for example two persons with N1c1 and N1c1a with identical Y-STR haplotype is much more distant related then what the identical haplotype suggest.

Haplogroup N subclades are currently defined with these main SNPs. These are included in FTDNA's current N subclade test:

N* (M231)
N1 (LLY22g)
N1a (M128)
N1b (P43)
N1b1 (P63)
N1c (M46/Tat,P105)
N1c1 (M178, P298)
N1c1a (P21)
N1c1b (P67)
N1c1c (P119)

Do you need to do a subclade test? Not necessarily. If someone with an identical or almost identical Y-STR haplotype has already tested you can instead rely on FTDNA's prediction with high confidence. To investigate this, logon to your FTDNA account and click "Y-DNA" and submenu "Haplotree". Then at the upper right click "Matches". 

Scientific literature list for your education and entertainment:
1. A counter-clockwise northern route of the Y chromosome haplogroup N from Southeast Asia towards Europe, Rootsi 2006
2. Human Y-Chromosomal Variation in European Populations MANDATORY READING
3. FINLAND: Regional differences among the Finns: A Y-chromosomal perspective
4. FINLAND: Analysis of 16 Y STR loci in the Finnish population reveals a local reduction in the diversity of male lineages
5. FINNO-UGRIC part I: Reconstruction of Maternal lineages of Finno-Ugric speaking people and some remarks on their Paternal inheritance
6. FINNO-UGRIC part III :Archaeogenetics of Finno-Ugric speaking populations
7. FINNO-UGRIC: On the phylogeographic context of sex-specific genetic markers of finno-ugric populations
8. LITHUANIA: Y-Chromosome and Mitochondrial DNA Variation in Lithuanians
9. FINLAND: Paternal and maternal DNA lineages reveal a bottleneck in the founding of the Finnish population
10. SWEDEN/SAAMI: Y-chromosome diversity in Sweden – A long-time perspective
11. SWEDEN/SAAMI: Y-chromosome diversity in Sweden – A long-time perspective SUPPLEMENTARY DATA
12. NORWAY: Geographical heterogeneity of Y-chromosomal lineages in Norway
13. NORWAY: Geographical heterogeneity of Y-chromosomal lineages in Norway SUPPLEMENTARY DATA
14. TURKEY: Excavating Y-chromosome haplotype strata in Anatolia
15. IBERIA: Recent Male-Mediated Gene Flow over a Linguistic Barrier in Iberia, Suggested by Analysis of a Y-Chromosomal DNA Polymorphism
16. Did you know Emperor Gaozu of Tang of China likely was a member of haplogroup N?
17. SIBERIA/JAPAN N3a, N3a1 and N1 haplotypes

Any donations will go to finance a Big Y 700 test or to investigate new SNP's for interesting candidates (group administrator excluded).