The cross-section of fundamental particle physics processes can be modified if they take place in a coherent electromagnetic background. Such backgrounds can be found around strongly magnetised neutron stars, along directions of symmetry in oriented crystals, in conducting cavities and, as this talk will focus on, laser pulses. The main concepts will be introduced, such as i) how the charge-field coupling can become non-perturbative in intense electromagnetic backgrounds; ii) how lasers can modify kinematics to open reaction channels; iii) why a 'strongly-coupled' phase of QED has been hypothesised. An overview of science goals and the differing approaches to physics at various facilities will be given and a conclusion drawn about the next steps the laser-particle community should take for progress to be maintained.