All right! Lab techs ("lab technicians"), RAs ("research assistants"), and lab managers are terms that are sometimes used interchangeably and sometimes refer to distinct positions. But most of the time, they refer to someone who has just graduated college and is working full time in a research lab before applying to graduate school.
Lab tech / RA / lab manager jobs are great. They give potential graduate students the opportunity to experience what research is like on a day-to-day basis; basically, you're in grad school but with administrative responsibilities. The amount of time you spent on administrative responsibilities compared to research depends on the lab. To the lab, your primary job is to manage the lab (administration) and research opportunities come second. To you, you want to do as much research as possible, and get an awesome letter of recommendation, before applying to graduate school. Luckily, everyone is completely aware of this situation, and a good professor will make sure that their lab techs also have the opportunity to do research.
Lab tech / RA / lab manager jobs are becoming the norm as an interim period between undergrad and grad school. They are almost always two-year positions, and you apply for them in Jan / Feb / March if you want to start in June when you graduate. Happily, they don't actually start appearing until February-ish, so you really don't have to get started early on them. In fact, they're pretty optimally timed because if you don't get into grad school (you'll know by the failure to receive interviews) then most people do a few years as a lab tech / RA / lab manager before reapplying and they get in the second time.
Why would you want to be a lab tech / RA / lab manager rather than just going straight into graduate school? Well, the first instance is if you don't know whether you want to get a PhD. And it's much better to sign up for a two-year position where you get PAID (lab techs / RAs / lab managers are real-life jobs) rather than dropping out of a 5-7 year graduate program where you're also getting paid, but, like, paid as a graduate student and working really crazy hours. (Graduate students get funding, but it's pretty much for housing and food. There's not a whole lot left over. And graduate students work constantly-- many RAs / lab techs / lab manager do as well, but it's not as mandatory as it is for graduate students.)
The second reason you might want to work as a lab tech / RA / lab manager is because you need to have more research experience before applying to graduate school. I was told that I needed to do an extra year or so before applying, and more and more people nowadays are doing extra work before graduate school as application processes become more competitive. Current professors did not need to be as qualified to enter graduate school as today's students (I've heard this from many professors), and as more people apply with two years of research experience and paper publications, it becomes less likely that people will be accepted straight out of undergrad. For most of the schools I interviewed at, undergrads were outnumbered or close to outnumbered by students who'd taken some time off to do research. When you train longer you ARE more qualified-- you know that you want to do research, you've lived the research life and done well, and you have excellent qualifications. Some people who went straight in have told me they regretted this choice mainly because they didn't have time to live "real life" before going straight back to being a student. That said, half of my graduate school cohort went straight from undergrad this year, and if you're qualified and know that's what you want to do, and you get in, I say go for it and skip the lab tech / RA / lab manager step.
I'd spend some time talking to professors about whether you should do a lab tech / RA / lab manager job or not. They're going to have a good perspective on whether you have enough research experience to be accepted to graduate school the first time, and whether it might be good for you personally to take some time off. It's different for everyone, though the trend is increasingly moving towards more people doing research.
When you're applying for lab tech / RA / lab manager positions, make sure to ask how much time you'll be spending on administrative things (e.g. ordering equipment, doing animal care, making sure ethics protocols go through and everything else it takes to keep a lab running). I don't know the ratios, but I think something like a 50/50 split is good? I'm REALLY not sure on that number though, I'd ask around and see what people are doing. The ratio depends a lot on the lab. Also, make sure you like the lab-- you're going to be in that workplace for two years (that's half of your undergrad. It's a LONG time) and you want to know that you're happy with the professor and happy with the people and happy with the work. (That glorious job when you get all at once...)
So how do you find these positions? There are things called "listservs" where jobs like these are posted. Your university department should also send out notices periodically to seniors. But I found most of my potential jobs just by checking professors' websites and seeing if they had openings. There will usually be a page on a lab's website that will say "Contact" or "Interested in the Lab?" and research positions are usually advertised there. Even if the lab doesn't explicitly state an opening (this will usually be the case), email the professor. In the email, you should include what you want (a position) and why you're qualified for it. This usually takes the form of a cover letter and CV. And if the lab has advertised a position, follow their additional instructions. I only applied for one of these positions, but after getting to the short-list I had to do a short coding test to make sure I was qualified. Different labs will have different ways of interviewing applicants. ASK FOR HELP FROM PROFESSORS WHEN DOING THIS. It's a job application, and you only get one shot at it because you're cold-emailing people, so it is very important you do it right the first time!
All right, I think that's about everything! Some things about terminology before finishing up. Sometimes, "lab tech" refers to people who are full-time employees who only do administrative things, and are usually older and not planning to go to graduate school. Sometimes "lab tech" refers to people who do all of the coding in a lab but don't do any science. Sometimes "research assistant" refers to undergraduate researchers and not people who are in the interim period after college. Lab manager usually refers just to the job I've been describing, but is sometimes less commonly used. Usage seems to depend on school and where you are regionally as far as I can tell.
That's all I've got! If you want to talk to someone more about lab manager positions, please email some of the people on the Ambassadors page. I'm not really qualified to tell you about it, since I didn't do one, but a lot of my friends have, including those in clinical positions (shoot me a message if you want their contact info). Best of luck with figuring out whether you want to apply and the application process!