Metalloids are groups of elements in the periodic table that have properties between the metals and the non-metals which apparently cannot be or hardly classified as either metal or non-metal. The elements included in this group are Boron (B), Silicon (S), Germanium (Ge), Arsenic (As), Antimony (Sb) and Tellurium (Te).
In comparison with metals*, metalloids are solid can be a conductor but in a fairly manner only. They also have higher densities compared to non-metals and have a metallic appearance. In contrast, metalloids are more brittle compared with metals which are ductile and malleable (if solid).
In comparison with non-metals, metalloids can be insulators and are brittle (if non-metals are in solid form). In contrast, non-metals are not as lustrous as metalloids and most of the non-metals are gasses.
Metalloids generally are located somewhere between metals and non-metals with electronegativity and ionization energy values.
*Some metals are liquid at or near room temperature (Hg, Fr, Ga, Cs).