Most modern radio recivers are not particular about their antennas. The person who makes radio a hobby will be more concerned about antenna performance than the receiver.
Most receivers marketed to the general public have their antennas built it. The typical AM broadcast band receiver has a coil of wire wound around a magnetic rod which is inside the cabinet or housing. This is usually all the antenna such a receiver needs for that band.
If the built-in antenna needs a boost, there's no way to connect directly to it. Most typically, a boost is required when the radio is inside a building which shields it from radio waves. The way to provide the boost is to run a few feet of wire outdoors, bringing one end inside and lay it over the top of the radio cabinet. Sometimes I listen to a distant broadcast station with the receiver located inside a metal building. I have some outside antennas for transmitting. To boost the broadcast band reception, I just lay the end of a coaxial cable feedline over the broadcast set and the improvement is tremendous.
The built-in broadcast band antenna is somewhat directional. Often a weak station comes in better if the receiver is rotated anywhere up to 90 degrees.
The built-in antenna is used on most receivers, both table models and portables.
Portable multi-band receivers typically have telescoping antennas mounted outside the case for shortwave and FM reception. Many also have jacks where external antennas can be plugged in.
My experience has been that external antennas plugged into the jacks are worthless. If the telescoping antenna is not good enough, make it better by making it longer with some wire. Sometimes only three or four feet of wire will make a huge improvement. The most convenient way to do this is to have a wire with an alligator clip on one end, and fasten it to the antenna with the clip.
The above applies to most radios marketed to the general public for home entertainment. There's another class of radios which are called communications receivers. Usually these do not have their own antennas. The user has to come up with an antenna.
A good communications receiver will usually have at least two provisions for attaching antennas. One will be a fitting for a coaxial cable, and the other will be for hooking up a length of wire.
As with the home entertainment receivers, a communications receiver is not very fussy about antennas. Any sort of antenna will usually work well, no matter the frequency on which it is designed to perform.
A simple wire hooked into the back of a communiciations receiver will pull in the signals, but it will also pull in noise created in the shack, like from a computer or light dimmers. A coaxial cable is shielded from these noises, so if it is run to an outside antenna, it will sound a lot better.
An outdoor antenna will usually work a lot better than one that is strung around indoors. Aside from interference generated inside the building, the structure will reduce the strength of signals coming through the walls. Brick, metal siding and foil-backed insulation will all reduce signal strength. Many homes are like shielded boxes, completely encased in metal.
What makes a good outdoor receiving antenna? Almost anything. I get good performance across the broadcast and shortwave bands with a dipole cut for transmitting on 20 meters, and also on a VHF ground plane for two meters. The receiver is not fussy.
Much has been written about building and tuning antennas for specific frequencies. This is important for transmitting antennas, because the antenna has to be just right to radiate the signal. It can also be important for tracking down a 100-watt signal from halfway around the world, but for reasonably strong signals it's not necessary. Beyond a certain point, bigger is not likely to be better.