What the terms actually require.
WHY IT MATTERS
Licence obligations attach to distribution and sometimes to modification.
WHAT LICENCES BROADLY DIVIDE INTO
Permissive licences Copyleft licences
WHAT PERMISSIVE LICENCES TYPICALLY REQUIRE
Retaining copyright notices and the licence text Acknowledgement, in some cases
WHAT THEY PERMIT
Use in proprietary software, including commercial products.
WHAT COPYLEFT LICENCES TYPICALLY REQUIRE
That derived works are distributed under the same licence That source code is made available to recipients
WHY THAT MATTERS COMMERCIALLY
Distributing software containing strong copyleft components may require releasing your own source.
WHAT VARIES BETWEEN COPYLEFT LICENCES
How far the obligation extends Whether it applies to linked code Whether providing software as a network service triggers it
WHY THAT LAST POINT
Some licences extend obligations to software accessed over a network, not only distributed.
WHAT TO ESTABLISH
Which licence applies to each component you use.
WHAT TO UNDERSTAND
Whether your use amounts to distribution.
WHY
Most obligations trigger on distribution rather than internal use.
WHAT COUNTS AS DISTRIBUTION
Supplying software to others Including it in a product Providing it to customers
WHAT DOES NOT, USUALLY
Internal use within your organisation.
WHY QUALIFIED
Some licences treat network provision differently.
WHAT TO NEVER DO
Assume a licence based on the project's reputation.
WHAT TO DO
Read the licence file in the actual version you are using.
WHY THAT VERSION
Projects change licences.
WHAT TO OBTAIN
Advice, where a component is significant to a commercial product.
