Instead of feeding the half wave at the centre where the current is high and voltage low and the impedance is around 70 Ohm, you feed it at the end where the voltage and impedance are very high (several thousand Ohms). You do this via a 49:1 (or 64:1) UNUN transformer.
The advantages of this ANT are that generally again like the dipole and GP does not require a ground or earth, though a line isolator is highly recommended especially at higher powers, and is often more convenient to feed the antenna at the end closest to the operating position.
Most of the useful radiation does not occur at the ends, but around the middle area of the length of wire, which should be cut to a half wave length for 30m. This means that you can feed it near ground level, and have it go straight up for several metres without any effects on radiation pattern, and likewise the end of the antenna could be bent to fit into your space.
It could go straight up a pole (or rope to a high tree branch) all the way to the top as a vertical, or it could go out of a building in a horizontal direction, or it could slope from the ground up toward a high support, or it could be in an inverted L shape, going up then across.
If you use it as a vertical and then go out as an inverted L from the top which will have the added benefit of pushing the useful current radiating section further up from the middle portion of the wire, as the horizontal part at the top may act as a capacitance hat.
Figuring out the radiation pattern of the EFHW is a more complex thing when not wholly vertical or horizontal, and you can experiment, but this ANT can bring good results in various directions or distances according to your set up.
A good idea is to use a line isolator (choke) with the EFHW as the radiating part, unlike with a dipole fed in the centre with coax far from the operating position, is close to you and the TX. Therefore you may experience RF burns, noise picked up on the outer of the coax that runs to the transformer, and/or interference to your microphone or electronic keying circuit, and almost certainly RF getting into the VSWR meter rendering its readings incorrect. This is why a line isolator (choke) is almost a must to have, certainly when not running QRP and portable.
A simple choke that would work from 7-18MHz would be 19 turns of RG58 on 4.25" (11cm) air cored, e.g. on a plastic pipe of around 11cm diameter. See: http://www.karinya.net/g3txq/chokes/
This ANT does not require an AMU (ATU) matching unit other than the 49:1 UNUN, and is nicely resonant at the half wave for which it is cut (around 15m on 30mb) and on multiples thereof. Thus, an EFHW cut for the lower part of 80mb will be resonant around all the bands from 10-80mb including at or near 30mb. One for 40mb will however not be resonant at 30mb. Those wanting a 30mb ANT will therefore likely want to cut it for 30mb and you'll find that with a tuner (ATU or AMU) you may be able to use it on the other HF bands, possibly including 40m.
If you need to shorten the antenna physically you could wind the wire around a former a few cm thick in the middle of the length of wire, experiment with the number of turns and diameter, please post any results in this forum. You could also make it work on 40m by adding a choke at the end with another short piece of wire that will be resonant on 40m but ignored on 30m.
Again any details from practical experiences and constructions tips on this would be helpful, G3OJV has a video that talks about these options.
I provide links to useful information below, and several good videos exist online explaining the EFHW. Please do not confuse this with the "random" wire end fed ANT which would need an UNUN of 9:1 and an AMU/ATU. That may be a much harder beast to tame and with much less predictable results. Here, we recommend the 30mb EFHW specifically as an ANT option for you.
Do not be put off by what others say as there are many strongly held (and sometimes no longer correct) opinions on end fed ANT. Practice and theory aren't always the same, and I know of many who get great results out of EFHW. Peter G3OJV has several helpful videos on the subject. Getting the feed point away from the house can also help to minimize any RFI issues, along with a line isolator (choke).
The usual addage applies: get as much of that wire as high up and in the clear as you can!
Useful links to further information:
http://www.karinya.net/g3txq/chokes/
https://vu2nsb.com/antenna/wire-antennas/multiband-efhw-antenna/
https://k7mem.com/Ant_End_Fed.html
"Magic numbers", lengths to avoid, charts to calculate
How to build Unun etc:
http://qrper.net/viewtopic.php?p=267#p267
Example of a transformer, but you can build them yourself: https://www.wireantennas.co.uk/unun?product_id=112?product_id=112
http://www.jumaradio.com/The-challenging-Unun-Transformer/
Good construction guide: https://www.hfkits.com/build-instruction-impedance-transformer-for-end-fed-antennas/
https://www.hfkits.com/end-fed-antennas-a-critical-view/
https://dxexplorer.com/49-1-impedance-transformer/
https://qsl.net/nf4rc/2020/ResonantEndFedUnUnConstructionManual.pdf
http://www.gnarc.org/wp-content/uploads/The-End-Fed-Half-Wave-Antenna.pdf
Search: "The End-Fed Half-Wave Antenna by Steve Dick, K1RF"