Most people know about the European Convention on Human Rights and the European Court of Human Rights which applies the Convention. The Council of Europe is the body which generated it, enforces it and runs the court and associated administration.
The background to it is in the post-war period: about the same time the United Nations in 1948 came up with its Universal Declaration of Human Rights, the UK, France, Germany and other European countries brought together a group of parliamentarians to plan a charter of rights and freedoms to ensure that there could never be a repeat of what happened in the 30s and the War. By 1950 this new body, the Council of Europe, had written the charter, i e the Convention (containing a statement of principles drawing on historical Bills and declarations of rights, and setting up the Court), ready to be ratified and implemented within three years by its dozen member states.
It's an international treaty with an international court to enforce rights of individuals in its (now 47) European member states. Not all member states have ratified all the Articles - or indeed all the additional Protocols that have grown up around it as amendments or expansion of rights. That includes the UK. It also has several non member affiliated states, e.g. the USA.
It's deeply embedded and has a massive influence in developing notions of rights and on the law in member states and more widely (I believe the EU requires Accession States to sign up to it.)
It continues to develop its interpretations of the Convention through the Court and its influence through its representative and administrative machinery and policy initiatives - the last item I read about, some time ago, was a drive to promote racial equality across the member states, which I believe was being pushed by a specific pressure group as well, and now we learn from the Debbie Hayton article, there's one about gender identity.