What's the purpose of SQL keyword "AS"?

Question

You can set table aliases in SQL typing the identifier right after the table name.

SELECT * FROM table t1;

You can even use the keyword AS to indicate the alias.

SELECT * FROM table AS t1;

What's the difference between them if any?

I see old DBA people tend to write statements without AS, but most of the new tutorials use it.

Update: I know what's the purpose of table and column aliases. I'm curious, what's the reason of having a separate keyword for setting aliases while it works without it as well.

Answer 1

There is no difference between both statements above. AS is just a more explicit way of mentioning the alias