You can use it to substitute but.
And if you can substitute "however" at the end, you can use also use "though."
Examples
Is not going to rain tonight, but it will be cloudy.
Is not going to rain tonight; it will be cloudy, though.
Is not going to rain tonight, it will be cloudy, however.
They played hard, but they didn't win.
They play hard; they didn't win though.
They play hard; they didn't win, however.
And finally, it can be used as emphasis to add confirmation or even ask something depending on the intonation of your voice.
your friend says, I'm working tomorrow, and you reply with,
You're coming to the party, though?
Is like saying, despite the fact you're working late, you're still coming, right?
Or if you say it without hesitation, and you state it as a fact, then you're telling your friend, yea, you're working late, but despite that fact, you're still coming.
You're coming to the party, though!
-"I don't remember packing my sandals and now I can't find them."
-"I saw you put them in the front of the luggage, though!"