In May 2023, I needed to present an application for a B1 Business / Conference visa for the USA.
I made this application as a Cameroonian from Canada. However, the procedure is almost the same regardless of the country where you live (nonetheless, depending on the country, there might be more or less available appointments).
The entry point is the DS-160 form to fill in. You can only book an appointment at the US embassy if you obtain a valid DS-160 number when you complete this form. The form can be quite tedious to fill out, with many sections and information to provide. Once you are done with the form, the next step is to book your appointment at the embassy on the ais.usvisa site. Generally, there are no available appointments for the US, don't ask why, it is crazy!!! You generally have around more than 2years delay to obtain an appointment. Needless to say, it's very discouraging. For example, I was asking for a visa to attend a conference in June 2023, and the next appointment was in 2025!
But don't panic. If the purpose of your travel is really important (I mean really really!), you still have the possibility to ask for an emergency appointment that needs to be motivated. The concern is that your demand only depends on the immigration agent that will evaluate your motivations 😅, so you shouldn't take it lightly. I recommend taking your time to write a proper and well-motivated demand where you clearly explain why you think your request must and should be approved. Do not hesitate to provide links to your event, personal website, etc.
After this expedite request, the embassy has up to 5 days to approve or reject your demand. If it is approved, the embassy will communicate a new appointment date (probably the one you asked for during your request).
One thing that is very annoying with this US procedure is that you should pay for the visa fees before booking an appointment, and these fees are not reimbursed! So, if your emergency appointment is not approved, we can say that you just lost your money uselessly (since you will not be able to attend the event for which you need the visa). And another funny thing: you are entitled to one priority request only!!
This is all for the online procedure.
The next step is the physical appointment at the embassy. You don't have the right to enter the embassy with any bag or laptop! So, please take only your documents with you and maybe a very small shoulder bag.
The interview generally takes only a few minutes (I'm not joking, it is probably less than 3 minutes!), where an immigration agent asks you about the motivation and the purpose of your travel. And if you are able to convince him...
What is interesting is that, unlike other country embassies, you know at the end of your interview if your visa is accorded or not.