Pure-blood, Half-blood, Muggle-born, Squib

[osotac]

Pure-blood---witch/wizard of 'pure'ancestry, without any Muggle 
ancestors whatsoever, as far as we can tell...
Pure-blood families:
Weasley family
Black family
Lestrange family
Malfoy family
Crouch family

Half-blood--at least one wizarding parent but at least one Muggle 
parent or grandparent.
Half-blood:
Tom Riddle---Muggle father/witch mother
Harry Potter---Muggle-born witch mother/ Wizard father
Seamus Finnegan---Muggle father/witch mother
Nymphadora Tonks---Muggle-born father/ pure-blood eitch mother                 

Muggle-born---wizarding person born of two Muggle parents.
Muggle-born:
Colin & Dennis Creevey
Lily Evans
Justin Finch-Fletchley
Hermione Granger
Ted Tonks

Squib---non-magic person born of wizarding parents, very rare 
occurence, more so than a Muggle-born witch/wizard.
Squib:
Arabella Figg
Argus Filch