(3) You can always type however in the search box to find
some helpful threads.
(4) Sometimes, we use however like this:
It is important to learn English; however, it is equally important
to know your first language well, too.
(a) however links two sentences together into one sentence.
(i) you must use a semicolon (;) in front, and you must use a
comma (,) after the word however in the kind of sentence that
I have given you.
(4) Sometimes however means something like it does not matter
However smart a person thinks she or he is, there are many things
that she or he does not know, so we must all be humble.
Thank you for the careful explication. I might --however unnecessarily -- point out that however can be inserted into the stream of a single independent clause, in which case it only requires a comma on each side.
"There was quite an uproar, however, when he went on to give his opinion about the handball of the Uruguayan player in the game against Ghana."
In this case, of course, the entire sentence is a follow-up to a previous sentence. And, come to think of it, since the sentences could have been linked a semi-colon, what I have written adds little, if anything, to what you have so nicely presented.