It is important to consider how you want your data to be reused. You can then apply a licence that most closely reflects those intended uses. Applying an explicit licence removes any ambiguity over what users can and cannot do with your data.
Lawyers can craft licences to meet specific criteria, but there are a number of open licences developed for widespread use that anyone can apply. There are many advantages to using standard licences rather than bespoke ones; as well as the benefits of enhanced organisational efficiency and cost saving, the use of standard licensing terms can lead to greater interoperability of data and increased user awareness of the licence terms, thereby enabling better compliance.
Standard open licences include: