Swept Wing: This design is the modern design of fighters and aircraft as it is the most widespread in both civilian and military use. Swept is meant to return the wings back. The design is important to the fighters' need to reach very high speeds. drag and from which the fighter can fly at high speeds and it is given good capabilities on high altitudes, such as this design f-16, f-18, su-27, the mig-15 is the first aircraft with this design

because in order to achieve high (supersonic) speeds you have to minimize the effects of shock waves.

1) To delay their development on the wings you would prefer to design the fighter jet with a sweptback wing (the increase of sweep angle is adversely proportional to magnitude of chordwise flow component on the wing), though this is at the expense of aerodynamic efficiency;

2) This will help you to reduce spanwise structural loading along the wing especially those that emerge at high speed maneuvers;

3) Design of directional and lateral control surfaces must consider the effects of wing sweep to enable effective controllablity at all flights modes;

4) To achieve high altitudes, due to low aspect ratio, fighter jet must develop high speeds, which again requires consideration of supersonic phenomena.

5) For fighter jets swept wings help to reduce their RADAR footprint, because they allow less reference area, airfoil is supersonic (sharp edges), and shorter straight edges.

6) In addition to other operational and technical characteristics such as better swarming capabilities, easy storage and taxiing, restricted aircraft carrier surface .. etc., that are better achievable by swept wings for a fighter jet.

You can tell what an aircraft is meant to do by its wings. General aviation trainers have straight wings as they fly at slow speeds. The faster the aircraft, the more sweep you want/need. It has to do with Mach effects and drag. When you go fast, lift isn't really the issue as such fighter wings are relatively small. For more details see: https://www.boldmethod.com/learn-to-fly/aerodynamics/wing-sweep/

https://www.flyingmag.com/why-are-wings-swept

https://history.nasa.gov/SP-468/ch11-3.htm