  We initiate the LISA template databank for stochastic gravitational wave
backgrounds sourced by cosmic strings. We include two templates, an analytical
template, which enables more flexible searches, and a numerical template
derived directly from large Nambu-Goto simulations of string networks. Using
searches based on these templates, we forecast the parameter space within the
reach of the experiment and the precision with which their parameters will be
reconstructed, provided a signal is observed. The reconstruction permits
probing the Hubble expansion and new relativistic DoF in the early universe. We
quantify the impact that astrophysical foregrounds can have on these searches.
Finally, we discuss the impact that these observations would have on our
understanding of the fundamental models behind the string networks. Overall, we
prove that LISA has great potential for probing cosmic string models and may
reach tensions as low as $G\mu =10^{-16} - 10^{-17} $, which translates into
energy scales of the order $10^{11}~\text{GeV}$.
