Oyster Card?

oyster works within London on tubes,buses,and (some)trains, all soon.It is cheaper than paying cash per journey ie a single bus trip with oyster �1.50, without �2.00. Also about 1/2 price underground.Daily capping bus �3.50,bus and tube �5.60. Weekly pes vary depending on zones required,zones 1_6. In Bath or Manchester they dont work at all.