As of mid-1012, paper tickets for the Metro are being phased out, and all fares have to be applied to re-usable plastic TAP cards, which cost $1 in addition to the fare (unless you're buying a monthly pass). This is not a big deal for regular users, but can be annoying if you're just in town briefly and only need one ride - ever, but it's still the most economical way to get from point A to point B, other than walking. During the transition period, machines at some stations still sell paper tickets, while others sell only TAP cards.
The easiest way to buy your Metro train tickets is to use cash in the ticket vending machines at each Metro station. The machines will return any change along with the ticket or TAP card. Most vending machines do NOT accept credit or debit cards.
Individual fares are good for two hours on one line in one direction. You can also buy Metro Day Passes in the Ticket Vending Machines.
On most Southern California buses, you can pay bus fare in cash deposited into a receptacle next to the driver or use the TAP card. The machine accepts dollars or coins. You can overpay if you don't have the exact change, but the bus driver cannot give change. You have to pay the base fare every time you get on a Metro bus. There are no transfers between Metro buses. However, you can get a Muni transfer to other local transit systems for $0.30. You can also purchase Metro Day Passes from bus drivers if you have $6 cash ($5 plus $1 for the re-usable TAP card).
Weekly and monthly Metro Passes and tokens must be purchased at Metro Customer Care Centers or various retail outlets.
Metro Tokens are good for one base fare ($1.50). They are sold in sets of 10 tokens.
Metro Day Passes, Weekly Passes, Monthly Passes and the EZ Transit monthly pass (for travel on Metro plus 14 local transit systems) are a convenient option for people planning to make extensive use of public transportation in LA for one or more days.