Endosymbionts play a major role in microbial ecology and host–microbe interactions, which has drawn a lot of attention to their molecular characterization. Numerous polymerase chain reaction (PCR)-based techniques are used to study endosymbiont genetic diversity and population dynamics. A useful technique for identifying genetic differences is PCR–restriction fragment length polymorphism (RFLP), which amplifies specific DNA fragments and then digests them with restriction enzymes. By examining terminal segments of bacterial 16S rRNA genes, the PCR–Terminal Restriction Fragment Length Polymorphism (T-RFLP) enhances community profiling. For microbial population research, PCR–Amplified Fragment Length Polymorphism (AFLP) is helpful since it provides thorough genomic fingerprints without requiring prior knowledge of the genome. PCR–Denaturing Gradient Gel Electrophoresis (DGGE) facilitates the detection of single-nucleotide polymorphisms (SNPs) by distinguishing DNA sequences according to their varying mobility under denaturing conditions. The structure and dynamics of microbial populations can be learned by the PCR–Temperature Gradient Gel Electrophoresis (TGGE) technique, which separates DNA molecules according to their melting patterns over a temperature gradient. By effectively investigating endosymbiont diversity, genetic variability, and evolutionary relationships, these molecular approaches contribute to gaining an understanding of microbial ecosystems.