Most radios, chargers, and lights all use coax power plugs. There are a number of different sizes with one being the most popular.
The 2.1mm x 5.5mm seems to be used the most. The 2.1 is the diameter of the center pin and the 5.5 is the diameter of the outside shell.
The 2.5mm x 5mm is also popular. They are not interchangeable.
There are a few other larger and smaller ones but the only ones you will really need to use is the 2.1mm size.
There is really no standard for the polarity of the center pin but most equipment use the center pin a positive.
You must use the exact charger or adapter that comes with your equipment unless you are confident your power source polarity and voltage are in the proper range or you will damage your equipment.
There are also differences in the center pin of the sockets. Some are solid and some are split. The split ones have a higher current rating and better, tighter contact.
There are some plugs (wire ends) that have a circular hole and some have a split tongue for better current handling. It is important that you do not use a connector with a split pin and split tongue together.
For heavier current connectors used on solar panels, charge controllers, AC power supplies, and 12 volt battery circuits there are three more types of connectors. SAE bullet, Anderson Power Pole, and XT60 connectors.
Each require a special crimping tool or are soldered to the wires. The crimping tools and these connectors are available from Amazon and Ebay.
The most popular type for Amateur Radio equipment and accessories is the Anderson Power Pole™. They come in 15, 30, and 45 amp sizes. They can be used in other various connections.
A common type of connector used on some solar panels are the Bullet SAE type. Caution should be taken when making jumper cables because the red on one side of cable end will be black on the other as shown in picture.
They should be wired so the +12 volt hot (source) side is the female end inside the rubber connector shell as shown on the right and the +12 volt (load) side is the exposed male on the left side.
A more recent type used on some charge controllers are the XT60 connectors shown below. They are made by Lorje.