In the old days, there were two ways to publish: with traditional houses, the optimal choice, or their ugly step-sister, vanity presses. Today, in addition to large and small traditional houses, there are various self-publishing options, including DIY platforms, self-publishing partnerships, also called assisted self-publishing, and, for self-publishers who want the publishing house experience, hybrid subsidy presses.
I personally chose self-publishing after research but I knew it would be hard. All the marketing and the effort is something I do. My editor helps me but being the author I call the shots. It's hard I will admit and I do not advise self publishing on people who have full time jobs, marriages or children. This is not a hobby. It's a full time gig. I choose this because really I have no other obligations beside school. I have no regrets but I do advise other writers to weigh all their options before they choose this path.