There are two sorts of parishes whose boundaries do not always coincide:
A civil parish is an independent local democratic unit for villages, smaller towns, and suburbs of urban areas. Each parish has a Parish (or Town) Meeting consisting of all its local government electors and most (where the electorate exceeds 200) have a Parish or Town Council. Over 13 million people live in such parishes.
The council is a small local authority. Its councillors are elected for four years at a time in the same way as for other councils. Bye-elections may be held to fill vacancies occurring between elections. The council is the corporation of its village or town. Each year the councillors choose a chairperson from amongst their number.
Parish councils have a number of formal powers. Many provide allotments, and look after playing fields, village greens and other types of leisure activities such as swimming pools. They have a hand in maintaining or guarding rights of way, bus shelters, public seats and smaller scale street lighting. Councils are often concerned with the provision of halls and meeting places.
The parish council can do these things by actually providing them itself or by financially helping someone else, such as a volunteer or a charity, to do them.
A variety of things. Some help social care schemes, or a local bus service. They make village surveys that inform planning authorities. Many provide car or cycle parks. Others provide public conveniences, litter bins and seats, and can prosecute noise-makers or litter bugs. Many appoint charitable trustees and school managers. Very often the cemetery or a closed burial ground, and perhaps the war memorial are managed by the Parish Council. Often, Parish Councils implement and co-ordinate crime prevention measures, as well as traffic calming initiatives. They have the power to improve the quality of community life by spending sums of money on things which, in their opinion, are in the interests of the parish or its inhabitants, and many kinds of activities are aided in this way.
Parish Councils are the most unbureaucratic and the cheapest kind of local authority in existence. Their funds are a tiny part of the council tax and they get no general government grant - so they have every incentive to keep expenditures low and be economical.
Parish Councils have lately become more important because a unitary authority can seem more remote.
The parish councillors know the villages and can (and increasingly often do) represent their views to other authorities like the Unitary Council, Health Authorities, Police and Fire Authorities. They are entitled to be consulted on planning applications, which include work to listed buildings and in conservation areas, and are often consulted on such things as schools and roads. They put the parish’s case at public inquiries. Recent moves from Government to greater 'localism' are set to increase the role of Parish Councils even further.
You elect its members every four years - you last did this in May 2017 - and you are encouraged to go to the annual parish meeting and to say what you think. You can also go to every meeting of the Parish Council and meet the Council members and listen to their business; see Public Notices for when these are. The accounts are strictly audited every year.