1) Space lattice –

The lattice is purely a mathematical abstraction. Space lattice is regular, periodic, repeated 3D array of those points selected in space such that irrespective of references, the neighbourhood or environment remains the same

2)  Unit Cell --

The unit cell may be defined as, the smallest repeating unit in space lattice which, when repeated over again, results in a crystal of the given substance.

3) Lattice Parameter –

Lattice Parameters –

The smallest cell which when repeated throughout space is called primitive cell. It is specified by axes a,b, & c called primitive axis while the magnitudes or dimension a,b,c, are called the lattice parameters.

In 3D, the unit cell is parallelopiped formed by the basis vector $\bar{a}, \bar{b}, \bar{c}$ the angles $\alpha , \beta , \gamma$. Together these six quantities are called lattice parameter or lattice constant.