This document discusses different techniques for digital image watermarking, including in the spatial and frequency domains. It provides an overview of watermarking concepts and applications. It then describes two watermarking algorithms - one that embeds watermarks in the spatial domain by modifying pixel intensities in selected image blocks, and another that embeds watermarks in the wavelet domain by modifying selected wavelet coefficients. Both algorithms are described step-by-step and include watermark insertion and extraction procedures. Results are provided showing the performance of the algorithms under different attacks in terms of normalized cross-correlation between the original and extracted watermarks.