The London Pass is a digital sightseeing credits package, offering access to over 90 major attractions in London like the Tower of London and the Westminster Abbey, with a single pass for potential savings. It comes in durations of 1 to 10 days and can be used on a smartphone. The pass functions on a credit system, where each £1 of attraction cost equates to one credit, with a maximum credit limit per duration. You can activate the pass for the number of consecutive calendar days purchased, starting from the first use.