「today」、「 nowadays, these days 」、または「 today 」は、「過去と比較して現時点で」を意味する副詞として使用できます。

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.

These days はより非公式です。

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 はもう少しフォーマルです：

Apartments today are often designed for people with busy lifestyles.

nowadays は使用できますが、 today や these days は使用できません。名詞の前の所有格 ‘s 構成、または名詞 of 後の of では使用できません。この使用法は非常に形式的です。

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.