The single ride ticket is called the t+. The cost is as you have said.
The t+ is valid on the tramway, bus, funicular, and métro. You may also use it on the RER (regional train) but for travel no farther than zone 1 or the city limits of Paris. It is incumbent upon the user to know the ticket´s RER limit and disembark before the train takes him beyond the validity of his ticket. Transfers are permitted bus to bus and RER/métro to métro/RER (within the stated RER distance restrictions). The ticket t+ is valid anywhere on the métro. A métro map is available here.
Métro usage is determined by each line´s endpoint indicating direction of travel. Tickets must be kept until exiting the bus or rail network at which time it is best to discard used tickets to preclude mixing them with unused tickets. There are garbage bins available at exits to properly dispose of used tickets.
Not a day pass, not a timed ticket.
I hesitate to mention this as it is a detail but the ticket t+ does have a time limit when using it in the métro. Métro travel must be completed within two hours of a tickets initial validation.
The same applies for buses (it's a bit more subtle, here a 90 minute timing applies)
The 90 minute limit for buses starts when a ticket is first validated and allows connections to be made during a 90 minute time frame. It is a boarding limit only, there is no maximum time validity for bus travel. Bus connections must allow for continued travel in the same general direction. You may not reboard a bus with the same route number. There are also special rules for night buses and airport buses.
At your option, you may purchase a Navigo Easy card (2€) and load your tickets electronically. This card may also be simultaneously loaded with one of the day pass options (Navigo Jour or Mobilis).