The censuses are one of the most useful resources for the family historian. Censuses from 1841 through to 1911 for the entire country are available online through sites such as Ancestry and FindMyPast. They were taken every 10 years through to the present day, with the exception of 1941, which wasn't taken because of the war. What many people don't realise is that there were earlier censuses which can contain useful information.
1841 was the first year in which the census taking was organised at the national level. The Government employed people to go around and collect the data about every person and where they were on the census night, 7th June. The collected data was copied into special enumerator's books, which were sent to the Government so that they could extract the data they required, such as population growth, numbers of workers of different sorts, numbers of children etc. The online images and their transcriptions are the pages of these enumerators books. The original collected data was mostly destroyed after it had been collated into the books. For more information about the UK censuses see Wikipedia.
Earlier censuses had been taken every 10 years from 1801. However, these were created differently. They were primarily concerned with counting the number of people and measuring population growth or diminution. To this end the Government decreed that the data should be collected at the local (parish) level. In each parish the churchwardens or the Overseers of the Poor were tasked with counting everyone in the parish. They had to count the number of households, and the number of males and females in each household, the numbers of adults and children and the numbers of workers in agriculture and manufacturing. They had to collate the data and send the numbers to the Government. How they collected the data was up to them.
Most decided it made their life easier if they noted the name of the head of the household with the collected numbers. Some decided it would be best to note the names, ages, sex and occupations of everyone in the household and then extract the required data from these notes.
Once the data had been collated and sent off, the original notes were either destroyed, kept by the officer concerned or stored in the Parish Chest with the other important parish documents. Therefore, unlike with the modern censuses, many of these original notes still exist and can be useful to the family historian.
The most definitive list of the available early census data is available as a large pdf file here.
From this document, the only existing examples of these early censuses for the Isle of Wight are Calbourne 1811, Ryde 1821 and part of the parish of Newchurch for 1821. Unfortunately, I think the part of Newchurch 1821 and the town of Ryde 1821 are actually the same document. For images and transcripts of the Calbourne 1811 and Ryde 1821 click on the links. Both of these only give the names of the heads of the households.
As well as the usual decennial censuses, there were also other population counts conducted for various reasons. Almost by accident I stumbled upon a document called "census of Calbourne re. Service with the Volunteers 1803". This was a time when the threat of French invasion seemed high and Volunteer forces were being raised throughout the country. The document is an absolute gem as it gives the names and ages of everyone in the parish, and identifies many of the relationships and occupations. See here for more information and images or here for a transcript.
I wonder how many more such documents are lurking in the Isle of Wight Record Office, and other Archives up and down the country?