A Group 4 element is the series of elements in group 4 (IUPAC style) in the periodic table, which consists of titanium (Ti), zirconium (Zr), hafnium (Hf) and rutherfordium (Rf).
All of these elements are classed in Group 4 because their valence shell holds four electrons. Rutherfordium can only be produced in the laboratory and has not been found in nature.