How are bacteria classified on the basis of number and distribution of flagella?

Based on flagella bacteria are classified into four categories.

i) Monotrichous  -  single flagellum on one side.
ii) Amphitrichous  -  on both the ends of the cell single flagellum is present.
iii) Lophotrichous  -  tow or more flagella at only one end of bacterial cell.
iv) Peritrichous  -  complete cell is covered with flagella.
v) Atrichous  -  cells with out flagella.

•  Function of flagella is locomotion.