Copyleft Compatibility
Some permissive free software licences contain clauses that make them incompatible with copyleft licences. One example is clauses requiring advertising materials to credit the copyright holder. Licences with this type of advertising clause include the 4-clause BSD licence, the PHP License, and the OpenSSL Licence.
Examples of permissive free software licences without advertising clauses are the MIT License, the 3-clause BSD license, and the Zlib License.
Some licences do not allow derived works to add a restriction that says a redistributor cannot add more restrictions. Examples include the CDDL and MsPL. However such restrictions also make the licence incompatible with permissive free software licences.
Read more about this topic: Permissive Free Software Licence