This is primarily focused at newcomers to the hobby, but I think it is important that even seasoned hams periodically review the ARRL BAND PLAN.
In our local area I make sure this is at least mentioned during Technician license classes. But many people don't go to classes, they memorize the question pool on their own and I don't know if they are exposed to concepts like the the ARRL band plan or not. I think it is vitally important that we remain a self regulated (for the most part) group and part of that is understanding where to operate.
So what is it ?
Well, usually any description of it starts off with saying that it is NOT law. This wasn't put out by the FCC. If you don't follow it, you probably won't be the target of enforcement action, but you will be guilty of being an asshole.
It is what is referred to as a "gentleman's agreement".  It's an attempt by civilized and educated men to sub-divide the ham radio frequency allocations granted to us by the FCC so that we all can enjoy the modes of our choice without interfering with other hams trying to enjoy the mode of their choice.

Even if you have never heard of the ARRL bandplan, you probably have encountered the idea that certain modes are known to hang out in certain parts of the band. Some of this is because of law, and some of this is because of the ARRL bandplan.
Some examples would be that the people operating PSK31 hang out on these frequencies, the guys that operate AM hang out on those freqencies, the Slow Scan TV guys hang out of some other frequency. There are a number of reasons for this: first of all, if you want to work someone using those modes, it's handy to have everybody congregated all in one small area so you can find each other. And also there is a less likely chance of interfering with people using other modes.

A couple  examples that probably need work. In other words common places where people interfere with each other either intentionally or not:
The "AM Window": there are a lot of guys that enjoy running old vintage gear that was common in ham radio before single sideband came about. Other guys on AM are running actual Broadcast transmitters from AM radio stations that have been converted to ham radio frequencies. The are typically on 7.290 during the day and on around 3.870-3.890 at night. There are other AM frequencies on other bands, but these are by far the most common. Virtually every time they get on the air, some asshole on SSB insists on starting a QSO right next to them. 80 meters is a big band. There is no reason why you have to be "that guy" and ruin someone elses fun because you insist on being an asshole.

Probably the most dramatic example I have ever heard of someone not following the bandplan is something I read on-line: A group of people, I believe in Texas, all got their ham licenses and bought HTs. It was some kind of group like a search and rescue group or something like that. They wern't really interested in ham radio, they just wanted to use HTs for some reason other than being radio hobbyists. Anyway, every month they conducted a drill over a weekend. They looked at the FCC rule book, saw where they were allowed to operate on whatever  band, they bought the HTs for,  they picked a frequency they were LEGALLY allowed to operate on and did their thing.   Ok, so far, so good.  The problem is that the frequency they had chosen was the input frequency to an amateur radio satellite. So on the weekend they had their drill,when this satellite made it's pass over north America, they wiped it out for everybody in North America. The local hams figured out what was going on and approached these guys and asked them to please switch frequencies. These guys told them to go pound sand, they were operating legally......... I guess it got resolved somehow or it may be internet bullshit, but it is a good example of what the bandplan is trying to prevent.

I could go on, but before you transmit, just sorta keep in mind that other people are also using the HF bands and they would appreciate your consideration of them just as much as you would appreciate their consideration of you. And if you have someone come on frequency and ask you to move because you are on an established frequency, like maybe a recognized SSTV frequency (and you are not using SSTV), thank them for pointing it out to you and  please move away.

If you start all sessions with "Is this frequency in use?" you will be 80% to being a good operator.

I  move for nets and for folks that have skeds.

Honestly it is my experience that someone from the group that thinks they own that space will VERY likely start tuning you up if you do not yield anyway, so what's the point?

It's a big spectrum, there's space somewhere.

I have the band plan taped just above my radio's where i can see it.

When asking if the frequency is in use on CW, you send QRL ?
If the frequency is in use, they will typically answer with the character "C" which means yes.


I have the ARRL Bandplan underneath a clear plastic desk blotter type of thing along with other stuff I might need to refer to.

Good post.

I try to run as far under the radar as possible.  Getting into battles with other hams is not something I am interested in.  One thing I wish is that my radios had limits that I could set where it will not let me TX outside of the bounds of my license.  I have caught myself accidentally listening down in the Advanced gap between general and Extra.  So far I have caught it and not transmitted.  I doubt anyone would hunt me down if I did but I want to keep in the correct general class areas.  

I have listened a few times to the digital frequencies and heard people tx voice.  Usually someone will call out that they are on the digital frequency and the interference ends.  Of the few times it has happened, if the person trying to correct the situation is polite, the interloper says thanks and moves on.  If the exchange starts out rude, it goes downhill fast.  You really do catch more flies with honey.  

Thanks 1M times for this!

The IC-7200 can do this.

I heard two Extras bragging about bashing a general who went down below 14.200 the other day.  Meh.

I know about the band edge beep but that does not limit.  Is that what you are referring to?  I am not seeing anything in the IC-7200 manual that would do it.

This is what I meant.

There is always someone listening.
When I was a novice, I heard an Alaskan station calling CQ. I was all excited and I worked him.
A local guy called me and told me I had just worked the guy out of my frequency allocation as a novice.
He was right. I worked him in the extra class portion of the band. I don't remember what band it was, but lets say he was on 21.010, and I thought he was on 21.110.

I actually appreciated him pointing it out to me. I had made a mistake and I was more careful in the future. I didn't intentionally violate the rules, it was an honest mistake which I learned from.
This whole thing works both ways: if someone screws up, point it out in a nice way. And if someone tells you, you screwed up; accept it as constructive criticism and learn from your mistakes. Every interaction with other people doesn't have to be a toe-to-toe confrontation.

Here is a decent online band plan reference.  It includes many of the nets.

http://www.bandplans.com/index.php?band=All

That is a far better chart than the one I posted.
I am going to print that, although the problem with it, is also it's greatest strength. It is so long, that you can't print it out and stick it on your desk: it's too big.


One thing that has always annoyed me to a small degree and this is just me and I am biased.

This particularly is an issue on 40 meters: The CW/Digital sub-band extends from 7.000 - 7.125 mhz.
When digital modes became as popular as they are now, it  sort of/kind of  became common practice that CW used the first 50 khz and digital stuff used the next 50 khz. Nice even split. Fair to everybody. Both are narrow bandwidth modes and you can squeeze a lot of QSOs into 50 khz.   (the top 25 khz is the old novice band and is commonly used today for that same purpose: new/slow CW ops tend to hang out there to work other new/slow CW ops, although they arn't restricted there, it just works out well).

However, many digital modes have decided that they are going to use frequencies in the lower 50 khz of the band.  For example a popular PSK31 frequency is down there. Why ? Now you get right back to interfering with other modes when there is plenty of room available to avoid this problem. Same situation occurs during digital contests. Digital stations stray way down into the first 50 khz of the band and screw everybody else. This is perfectly LEGAL to do, but is it the right thing to do ? Is it a good operating practice ?

Again, whether you are a digital guy, a CW guy, or both: try to operate so as not to interfere with other stations who are just trying to have fun like you are.

which band plan, if I may ask?