Abstract: Mars lacks a global intrinsic magnetic field but retains localized crustal magnetic fields that are particularly strong in the southern hemisphere. The solar wind therefore interacts directly with the ionosphere, producing a bow shock, a magnetosheath, an induced magnetopause, an ionopause, and a draped magnetotail. Under ordinary conditions the presence of a clear ion-composition boundary prevents solar-wind plasma from penetrating deep into the ionosphere in large numbers, so that energy and momentum are exchanged mainly through electromagnetic processes such as pickup by the solar wind convectional electric field, ambipolar acceleration, wave-driven heating, magnetic reconnection, and boundary-layer instabilities. Open magnetic field lines that connect the solar wind to the ionosphere, however, allow hot solar wind plasma to enter the ionosphere along the field. Such open lines can be formed by reconnection at the induced magnetopause or by the direct entry of the interplanetary field into regions of weak crustal field in the northern hemisphere; flux ropes and flux tubes are two common carriers of this connectivity. Xu et al. (2024) and Yang et al. (2026a) proposed a fundamentally new mechanism, termed siphoning escape, that can operate across collisionless and collisional plasmas linked by the same magnetic field lines. Xu et al. (2024) reported an open flux-rope event in which proton density rose while temperature fell sharply and hot protons and cold heavy ions streamed in opposite directions. Yang et al. (2026) further showed that the same process occurs inside an open flux tube over a weak northern crustal field region, demonstrating that the helical structure of a rope is not required. In both cases hot solar-wind protons enter the lower ionosphere, collide with cold heavy ions and neutrals, and transfer energy and momentum directly; the cooled protons create a pressure gradient that continuously draws additional hot sheath protons into the same channel while the heated heavy ions escape outward. The two events share clear observational diagnostics: elevated proton density, strongly reduced proton temperature, counter-streaming of hot protons and cold heavy ions, and open topology confirmed by photoelectron peaks and the aluminum edge. These signatures distinguish siphoning escape from ordinary particle precipitation on residual open field lines. Quantitative reconstruction of a single flux-rope cross section yields an instantaneous oxygen loss rate of order 10²³ s⁻¹; the flux-tube event gives a lower but still non-negligible estimate. If open flux tubes are common in the northern hemisphere, the integrated contribution of siphoning to global ion loss may be substantial. The mechanism is essentially an energy exchange between collisionless and collisional plasmas connected by the same open magnetic field line. Similar processes may occur not only in the Venusian ionosphere and the terrestrial cusp but also in other astrophysical environments; differences in escape speed and magnetic-field structure, however, caution against direct transplantation. Building on the two studies, this paper systematically reviews the physical picture, key observational evidence, and quantitative estimates of siphoning escape and discusses its contribution to Martian atmospheric loss.