A directive is a type of EU decision.
Directives are to be transferred into national law through the member states' parliaments and governments within 18 months. If a country refuses to adopt a directive, it may become law in that particular country anyway. It the rules are sufficiently precise, they may be looked upon as directly applicable.
Through the years, the EU Court has proclaimed many directives to be directly applicable and even declared that countries are liable to pay compensation if they have not implemented a directive in time.
Directives are normally transformed into national laws by the national parliaments or most often by the governments through delegated acts.
The EU Constitution proposes renaming directives as 'framework laws'. A framework law binds the member states to achieve certain targets, but it is not directly binding as are regulations which are now to be renamed 'laws'.
The Democracy-Forum proposes to scrap all directives and change them into non-binding recommendations. When a binding effect is desired a real law has to be adopted.