DNA (deoxyribonucleic acid) - The molecule that encodes genetic information. DNA is a double-stranded molecule held together by weak bonds between base pairs of nucleotides. The four nucleotides in DNA contain the bases: adenine (A), guanine (G), cytosine (C), and thymine (T). In nature, base pairs form only between A and T and between G and C; thus the base sequence of each single strand can be deduced from that of its partner.

polymorphism - Difference in DNA sequence among individuals. Genetic variations occurring in more than 1% of a population would be considered useful polymorphisms for genetic linkage analysis.

haplotype - 1  A combination of alleles (for different genes) which are located closely together on the same chromosome and     which tend to be inherited together.  In other words, sets of nearby SNPs on the same chromosome that are inherited in blocks.
                   2   A group of alloantigens which are produced by the same allele or a group of closely related genes.

haplotype - your set of results on whatever markers were tested.Haplotypes using the DYS 
markers can change over the course of a few hundred years, and they are much more specific and useful in the genealogical time frame. 

Haplogroups are actually defined in a different way,by markers (called SNPs or UEPs) which change very slowly, so they preserve signals of what happened thousands of years ago.

SNP - single nucleotide polymorphisms - Sites in the DNA sequence
where individuals differ at a single DNA base. 

alleles -  Alternative forms of a genetic locus; a single allele for each locus is inherited separately from each parent (e.g., at a locus for eye color the allele might result in blue or brown eyes).

locus (pl. loci) - The position on a chromosome of a gene or other chromosome marker; also, the DNA at that position. The use of locus is sometimes restricted to mean regions of DNA that are expressed.

expression (gene expression) - The process by which a gene's coded information is converted into the structures present and operating in the cell. Expressed genes include those that are transcribed into mRNA and then translated into protein and those that are transcribed into RNA but not translated into protein (e.g., transfer and ribosomal RNAs).

markers - Chromosome changes that do occur from generation to generation.

meiosis - The process by which the chromosome number, 46,  is halved and chromosomes are sorted and packaged to be passed on to an organism's offspring. This is called a haploid cell as there only 23 chromosomes. The male sperm and female egg are haploid cells. Fusion of the two haploid cells gives one cell with 46 chromosomes, this is called a zygote which develops into a fetus.

mitosis - Normal cell division where the human cell divides rebuilding two cells of 46 chromosomes each.