We can use nowadays, these days or today as adverbs meaning ‘at the present time, in comparison with the past’:
I don’t watch TV very much nowadays. There’s so much rubbish on. It’s not like it used to be.
Young people nowadays don’t respect their teachers any more.
Take care to spell nowadays correctly: not ‘nowdays’.
These days is more informal:
These days you never see a young person give up their seat for an older person on the bus. That’s what I was taught to do when I was a kid.
Pop singers these days don’t seem to last more than a couple of months, then you never hear of them again.
Today is slightly more formal:
Apartments today are often designed for people with busy lifestyles.
We can use today, but not nowadays or these days, with the possessive ’s construction before a noun, or with of after a noun. This use is quite formal:
Today’s family structures are quite different from those of 100 years ago.
The youth of today have never known what life was like without computers.
We don’t use nowadays, these days or today as adjectives:
Cars nowadays/these days/today are much more efficient and economical.
Not: The nowadays cars / The these days cars / The today’s cars …