A rhombus has both diagonals, and the midpoints of opposite sides are joined by two more lines through the centre. How many triangles are in the figure?

The four lines through the centre cut the rhombus into 8 small triangles. Two neighbours inside one quarter make the 4 quarters of the rhombus, and the 4 halves cut by the diagonals are triangles too. Total $8+4+4=16$.