It highlights those journalists who cover the white house, in particular, and any journalist who covers politics in general. Various national politicians working in congress, the POTUS, and several celebrities are typically invited, with one invited comedian specifically to host and to roast the POTUS and potentially other politicians in attendance. Awards to winning journalists are given out as well.

Since trump never attended them before, he wasn't originally expected to attend. However, after he accepted, they replaced the usual comedian with a magician act so as not to "offend the notoriously thin-skinned monster in the white house".

So weird that they actually thought trump wouldn't go on the offensive!