Colloidal　particles　can　be　adsorbed　at　fluid-fluid　interfaces,　a　phenomenon　frequently　observed　in　particle-stabilized　foams,　Pickering　emulsions,　and　bijels.　Particles　adsorbed　at　interfaces　exhibit　unique　physical　and　chemical　behaviors,　which　affect　the　mechanical　properties　of　the　interface.　Therefore,　interfacial　colloidal　particles　are　of　interest　in　terms　of　both　fundamental　and　applied　research.　In　this　paper,　we　review　studies　on　the　adsorption　of　colloidal　particles　at　fluid-fluid　interfaces,　from　both　thermodynamic　and　mechanical　points　of　view,　and　discuss　the　differences　as　compared　with　surfactants　and　polymers.　The　unique　particle　interactions　induced　by　the　interfaces　as　well　as　the　particle　dynamics　including　lateral　diffusion　and　contact　line　relaxation　will　be　presented.　We　focus　on　the　rearrangement　of　the　particles　and　the　resultant　interfacial　viscoelasticity.　Particular　emphasis　will　be　given　to　the　effects　of　particle　shape,　size,　and　surface　hydrophobicity　on　the　interfacial　particle　assembly　and　the　mechanical　properties　of　the　obtained　particle　layer.　We　will　also　summarize　recent　advances　in　interfacial　jamming　behavior　caused　by　adsorption　of　particles　at　interfaces.　The　buckling　and　cracking　behavior　of　particle　layers　will　be　discussed　from　a　mechanical　perspective.　Finally,　we　suggest　several　potential　directions　for　future　research　in　this　area.