Since the Democrats in congress refused to sign onto a bill fully funding the government last Tuesday, the federal government has shut down non essential programs. This isn't surprising; the use of a government shutdown as a last chance attempt by a minority party to gain something politically have been around since the 1980's, and it was really turbocharged in the 90's when Republican House Speaker Newt Gingrich called for one that lasted 21 days (before that they usually lasted only a day or two).
Shut downs are a tricky thing with the public, who usually say that they want congress to accomplish things, but then are divided over just what they want done. Gingrich's shutdown was seen as a failure for him, cementing his image as a bomb throwing extremist, especially because he called for it more out of pique than any actual political issue (during a flight on Air Force One, then President Bill Clinton did not allow him to sit in the front of the plane or exit from the front).
The last shutdown was made by the Democratic party in 2019, and it lasted a whopping 35 days, making it the longest ever. The subject was immigration, with the Democrats refusing to pay for President Donald Trump's border wall with Mexico and Trump eventually giving in and removing funding for the wall from the budget.
This time the Democrats are trying to prevent cuts in Obamacare spending that will result in the healthcare premiums for millions of Americans going up, with some even doubling. The Republican party has countered by saying that the Democrats want to use federal funds to provide healthcare for undocumented immigrants. Both sides are clearly playing up to what are seen as their strongest issues, with Democrats defending people's healthcare and Republicans bashing undocumented (or "illegal") immigrants. For the record, the Republicans are straight up lying about the federal spending funding healthcare for the undocumented, but it's a powerful lie.
Personally, I think the Democrats are right to stand up to Trump and the Republicans over this issue, even though shut downs are always messy. Democratic voters have felt powerless ever since Trump took office again and started moving the country towards an autocratic system. (I never thought in my lifetime that we would have masked government agents racially profiling people and then grabbing them off the street in this country, but here we are!). Standing up to Trump and shutting down the government is the least that the Democrats can do, and using healthcare costs, a simple, relatable issue, makes sense. And the fact that Republicans have resorted to lying about healthcare for the undocumented instead of actually defending the spending cuts on their own supposed merit shows how little they have to stand on here. Put simply, the Democrats want Americans to not have to spend more money on their healthcare, and Republicans don't, even if they won't admit it. (Bernie Sanders and Acacia Ocasio-Cortez explained it all well in this this 3 minute video
That said, Trump is using the shutdown as an excuse to fire more government workers and cut already appropriated spending going to blue cities and states, engaging in the same kind of revenge based policies that have always driven him. But Trump was already doing these things, and many of those fired workers have already sued him in court, so he's not really getting that much out of it.
The irony here is that the Democrats are actually doing the Republicans a favor; if the Dems had just let the healthcare cost increases pass, angry voters would have blamed the Republicans for being in power and voted against them strongly in the upcoming midterms. But the Dems, as weak and ineffectual as they may seem, actually care about voters who aren't rich and want to make their lives better, even the ones in red states. Hopefully, they will win this shutdown with some kind of compromise from the Republicans, because this issue is really a moral one.