There are a range of different train ticket types that you can buy...
Advance - Buy in advance, sold in limited numbers and subject to availability. These tickets are only valid on the date/train specified.
Off-Peak - Buy any time, travel off-peak only.
Anytime - Buy any time, travel any time.
Season - Unlimited travel between two stations for a specified period.
Rovers and Rangers - Unlimited travel within a specified area. There may be a few time restrictions on when you can travel.
Remember, some train tickets are only valid for particular train operators. Please be careful to check in advance so you don’t get caught out and potentially risk having to buy a new ticket for the full price!