Captioning aircraft photos can be a bit daunting especially if you are not an aircraft nut and barely know the difference between a Boeing and a Bolkow.
Every civilian aircraft carries a prominently displayed registration. In the UK this starts with G- . All countries have their own prefix (See full list). Type the registration into Google and you will usually find references to that aircraft.
A Google search also works for most military aircraft which carry a more discreet serial number on the rear fuselage. You can improve your search results by putting the aircraft type in, if you know it, as well as the serial or registration.
More photographs from Airshows
The only exception to this are preserved military aircraft that are in civilian ownership and displayed in a military colour scheme. Often this paint job was never worn by that aircraft or occasionally not even by that type of aircraft. However a search using the displayed serial will usually bring up correct results
The problems start with the results of your search. Many photographers haven’t got the slightest idea what they have photographed so their captions often aren’t accurate. There are several sites that usually have accurate caption info and these including Airliners (also covers some military aircraft)and Air Britain.
By checking between these two you can generally get accurate info and identify the specific Mk (Mark) of an aircraft*. You’re probably not going to worry about constructors numbers or the minutiae of sub marks (I don’t) but a little work will save you looking a wally but calling a Hurricane a Spitfire.
The full story of N3200 the Spitfire lost for almost 50 years
*Aircraft such as the Spitfire progressed through a range of marks from the Mk1 right up to the Mk24 with side shoots of Seafires. These were significantly different aircraft so it is worth identifying the specific Mk.