Finding people that still alive

Hi guys, I spend aroun 3 y trying to find informations about my ancestors, but it is so hard because I have no enough informations about them. But I have some doubt, why do we have records from the past, but from people thar still alive iin around 50 they dont?
Answers
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This is normally for privacy/data protection reasons (consider in particular that the published personal information of living people can be, and very frequently is, misused by criminals; but many people, justifiably, simply don't want their information or their family's information plastered over the internet if it can be helped).
The exact rules for information collected by jurisdictions vary by jurisdiction and by record type. For example, UK censuses are not available until 100 years have elapsed. There will be still-living people on the publicly available 1921 census; and different rules apply (for reasons which escape me) to the UK 1939 Register, which has been available for ages. Much more recent England and Wales BMD information, however, /is/ available.
You may find more information is available via the record custodian's office (perhaps only to bona fide relatives).
Privacy is also why access to the Family Tree profiles of living persons is so tightly controlled.
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Mandy does an excellent job of pointing out the probable reasons for information on the living being rather more difficult to find. It really does make a difference when it comes to different jurisdictions - not just countries but, say, even states within the United States - on how recent local / national legislation allows for public access to more recent events.
In the US, there a a "72-year rule" with regards to publication of census records, whereas in the UK such records are not available for general release until 100 years have passed, so far more chance of currently seeing details of the living if your relatives were resident in the US up to 1950.
There is a lot of inconsistency when it comes to privacy considerations, even within my home country. For example, the official government agency "GRO" website shows details of births up to 2023, but only shows the child's mother's maiden name in their index up to 1925. However, the FreeBMD website somehow is "allowed" to go against this apparent "100 year rule" by publishing the mother's maiden name right through to the 1990s. The 1939 National Register has names redacted for individuals born under a hundred years ago, unless there is proof they are deceased (well, that's in theory, at least).
I would advise newspapers as being an excellent source for obtaining material about the living. There are websites like newspapers.com and (in the UK) BNA which have recently published newspaper articles (though coverage is very patchy) that would include birth and marriage announcements and obituaries - the last category often mentioning many relatives that are still alive. Papers also contain more "personal" articles, too, of course - so, as an example, I discovered one recently on an uncle who had been involved in a road accident, not too long ago.
In summary, the main reason for one often finding difficulty in accessing such records is, as Mandy suggests, the privacy factor. However, there are plenty of sources, depending on the country in question. Perhaps it would help if you could be more specific here, by saying where exactly is the geographical area on which you are focussed.
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