A haplotype (Greek haploos = simple) is a combination of alleles at multiple linked loci that are transmitted together. Haplotype may refer to as few as two loci or to an entire chromosome depending on the number of recombination events that have occurred between a given set of loci. The term haplotype is a portmanteau of "haploid genotype."
In a second meaning, haplotype is a set of single nucleotide polymorphisms (SNPs) on a single chromatid that are statistically associated. It is thought that these associations, and the identification of a few alleles of a haplotype block, can unambiguously identify all other polymorphic sites in its region. Such information is very valuable for investigating the genetics behind common diseases, and is collected by the International HapMap Project.

Haplotype Resolution

Main article: Genealogical DNA test UEP results (SNP results)
The other possible part of the genetic results is the Y-STR haplotype, the set of results from the Y-STR markers tested.
Unlike the UEPs, the Y-STRs mutate much more easily, which gives them much more resolution to distinguish recent genealogy. But it also means that, rather than the population of descendents of a genetic event all sharing the same result, the Y-STR haplotypes are likely to have spread apart, to form a cluster of more or less similar results. Typically, this cluster will have a definite most probable center, the modal haplotype (presumably close to the haplotype of the original founding event), and also a haplotype diversity - the degree to which it has become spread out. The further in the past the defining event occurred, and the more that subsequent population growth occurred early, the greater the haplotype diversity for a particular number of descendents will be. On the other hand, if the haplotype diversity is smaller for a particular number of descendents, this may indicate a more recent common ancestor, or that a population expansion has occurred more recently.
It is important to note that, unlike for UEPs, there is no guarantee that two individuals with a similar Y-STR haplotype will necessarily share a similar ancestry. There is no uniqueness about Y-STR events. Instead, the clusters of Y-STR haplotype results inheriting from different events and different histories all tend to overlap.
Thus, although sometimes a Y-STR haplotype may be directly indicative of a particular Y-DNA haplogoup, it is in most cases a long time since the haplogoups' defining events, so typically the cluster of Y-STR haplotype results associated with descendents of that event has become rather broad, and will tend to significantly overlap the (similarly broad) clusters of Y-STR haplotypes associated with other haplogroups, making it impossible to predict with absolute certainty to which Y-DNA haplogroup a Y-STR haplotype would point. All that can be done from the Y-STRs, if the UEPs are not actually tested, is to predict probabilities for haplogroup ancestry (as this online program does), but not certainties.
A similar scenario exists for surnames. A cluster of similar Y-STR haplotypes may indicate a shared common ancestor, with an identifiable modal haplotype, but only if the cluster is sufficiently distinct from what may have arisen by chance from different individuals historically having adopted the same name independently. This may require the typing of quite an extensive haplotype to establish, which has fuelled DNA testing companies to offer ever-larger sets of markers - 24 then 37 then 67, and perhaps soon even more.
Plausibly establishing relatedness between different surnames data-mined from a database is significantly harder, because now it must be established not that a randomly-selected member of the population is unlikely to have such a close match by accident, but rather that the very nearest member of the population in question, chosen purposely from the population for that very reason, would even under those circumstances be unlikely to match by accident. This is for the foreseeable future likely to be impossible, except in special cases where there is further information to drastically limit the size of that population of candidates under consideration.

See also
The following software is available for estimating hapltoypes
The following software is available for testing haplotypes for disease associations

snphap — EM based software for estimating haplotype frequencies from unphased genotypes.
Haploview — haplotype based association analysis.