Strong gravitational lenses provide unique laboratories for cosmological and astrophysical investigations, but they must first be discovered – a task that can be met with significant contamination by other astrophysical objects and asterisms. Here we review strong lens searches, covering various sources (quasars, galaxies, supernovae, FRBs, GRBs, and GWs), lenses (early- and late-type galaxies, groups, and clusters), datasets (imaging, spectra, and lightcurves), and wavelengths. We first present the physical characteristics of the lens and source populations, highlighting relevant details for constructing targeted searches. Search techniques are described based on the main lensing feature that is required for the technique to work, namely one of: (i) an associated magnification, (ii) multiple spatially-resolved images, (iii) multiple redshifts, or (iv) a non-zero time delay between images. To use the current lens samples for science, and for the design of future searches, we list several selection biases that exist due to these discovery techniques. We conclude by discussing the future of lens searches in upcoming surveys and the new population of lenses that will be discovered.

强引力透镜为宇宙学和天体物理研究提供了独特的实验室，但它们必须首先被发现——这项任务可能会受到其他天体物理物体和星体的严重污染。在这里，我们回顾了强大的透镜搜索，涵盖各种来源（类星体、星系、超新星、FRB、GRB和GW）、透镜（早型和晚型星系、星系团和星团）、数据集（成像、光谱和光曲线）和波长。我们首先介绍镜头和来源人群的物理特征，强调构建有针对性的搜索的相关细节。搜索技术是根据该技术工作所需的主要透镜特征来描述的，即以下之一：（i）相关的放大倍数，（ii）多个空间分辨图像，（iii）多个红移，或（iv）图像之间的非零时间延迟。为了将当前的镜片样本用于科学和未来搜索的设计，我们列出了由于这些发现技术而存在的几种选择偏差。最后，我们讨论了即将进行的调查中镜片搜索的未来以及将发现的新镜片群体。